I’m making this page a spot for compiling in one place all the most usefull information that I find online about the various malts and grains used in brewing. Information sources are cited below.
Pilsner Malt (aka Lager Malt)
Typical Colour: 2 Lovibond, 3-4 EBC
Common Brands, Variations: Weyermann Pilsner, Weyermann Bohemian Pilsner, Gladfield Lager Light, Gladfield Pilsner, Malteurop Pilsner, Thomas Fawcett Lager Malt
Lager malt can be used to produce ales as well as lagers. The name comes from the fact that pale lagers are the most common style of beer and this is the malt type most commonly used to produce them. Because it tends to be the most available malt, it is used for nearly every other style also. Logically, if you intend to brew a pale lager, you would be best served by using lager malt.
After germination, lager malt is carefully heated in a kiln to 90F for the first day, withered at 120-140F for 12-20 hours and then cured at 175-185F for 4-48 hours depending on the maltster. This produces a malt with fine mild flavor and excellent enzyme potential. It is used as the basis of most of the world’s beers in conjunction with specialty malts for added flavors. 
Pale Malt (aka Pale Ale Malt)
Typical Colour: 3 Lovibond, 5-7 EBC
Common Brands, Variations: Thomas Fawcett Golden Promise, Bairds Maris Otter, Bairds Pale Ale Malt, Malteurop Pale Malt, Malteurop Mild Ale Malt, Weyermann Pale Malt, Gladfield Pale Malt
This malt type is kilned at higher temperatures than lager malt, giving a slightly toastier malt flavor well suited to Pale Ales.
Typical Colour: 3 Lovibond, 4-5 EBC
Common Brands, Variations: Weyermann Wheat Malt, Gladfield Wheat Malt
Wheat has been used for brewing beer nearly as long as barley and has equal diastatic power. Malted wheat is used for 5-70% of the mash depending on the style. Wheat has no outer husk and therefore has fewer tannins than barley. It is generally smaller than barley and contributes more protein to the beer, aiding in head retention. But it is much stickier than barley due to the higher protein content and may cause lautering problems if not given a “Protein Rest” during the mash. 
These malts are commonly produced by increasing the curing temperatures used for base malt production, but can also be produced by toasting finished base malts for a period of time in an oven. 
Kilned Malts need to be mashed.
Typical Colour: 25 L
Common Brands, Variations: Dingemans Biscuit Malt
This fully toasted, lightly roasted malt is used to give the beer a bread and biscuits flavor. It is typically used as 10% of the total grain bill. Gives a deep amber color to the beer. 
Biscuit malt is actually a type of roasted malt, but is roasted to a very light degree at around 25-30° Lovibond. Roasting temp is around 350°F, which puts it somewhere between a high-kilned malt like Munich malt, and a roasted malt like pale chocolate, which might give you some idea of its characteristics and usage. It is a Belgian malt, so it can be used in a number of Belgian ales, as well as most English and American ales. The flavor may be a bit strong for most lagers, but light-colored or dark ales of almost any nature can make a home for biscuit malt. You can pair it with dark roasted malts for some depth of flavor, or in something like a pale ale to add some toasty, bready character without adding color.
Biscuit malt is aptly named for the biscuity flavor it imparts. It’s also sometimes described as a “saltine cracker” flavor (which I think is more fitting than “biscuity”). After crystal malt, I would guess that this is one of the most commonly used specialty malts, but as a new all-grain brewer, I remember being a bit gun shy about using it. While you can go overboard with biscuit malt, it’s not as strongly flavored as some specialty malts. One pound (or around 10% of the grist by weight) is about the most you would ever want to use in a five gallon batch, and about a half or a quarter of a pound is enough to get some of that complementary, biscuit malt goodness. I would recommend using this great malt with responsibility while you’re getting a feel for it. Some people will add biscuit malts to low-gravity bitters, milds, and brown ales to increase the malt component of beers with small bills. If you want a really malty beer, and you’re already brewing something that’s 1.070, adding biscuit malt may create that overly malty or cloying perception that some people associate with biscuit malt. So keep in mind what sort of beer you’re using it in, and how much malt and biscuit character will already be coming from the base malt or the malt extract. 
Typical Colour: 25 L
Common Brands, Variations: Briess Victory Malt
This roasted malt is similar in flavor to Biscuit but gives a more nutty taste to the beer. Victory adds orange highlights to the beer color. 
Victory Malt is of US origin. Similar in color to amber and brown malt, it is often an addition to American brown ale.
Typical Colour: 10 L, 16 – 23 EBC
Common Brands, Variations: Weyermann Munich Type I (light), Weyermann Munich Type II (dark), Malteurop Munich Malt, Gladfield Munich Malt
This malt has an amber color and gives a very malty flavor. This malt has enough diastatic power to convert itself but is usually used in conjunction with a base malt for mashing. This malt is used for Oktoberfest-type beers and many others, including pale ales. 
To understand Munich malt and how it differs from ordinary pils or ale malts, we must first understand how it is made. Like all European malts, Munich malts are made by steeping two-row barley in warm water and nurturing it through a warm germination phase; The resulting green malt is kilned under carefully controlled temperature and time requirements to yield a particular malt that has specific color and chemical composition. Different styles such as pils, caramel, black patent, or Munich malt are made by varying the temperature and duration of the kilning or by allowing the malt to be steeped warm before final drying to bring out the sugars. Pils malt is characteristically light-colored and high in enzymes. To make pils malt, green malt is kilned at 85°C to yield a malt of between 1 and 3° SRM (Lovibond). Munich malts, on the other hand, are meant to be much darker, typically around 7° SRM; they are also available in even darker versions of between 10 and 20° SRM. To achieve these colors, the green malt is “stewed” under progressively higher air temperatures, which promotes a degree of saccharification of the malt before it is finally kilned at 100°C. The longer the malt is held at 100°C, the darker the Munich malt will be.
In the beginning of the kilning process, green malt has considerable moisture content, typically in the 45–50% range. Early in the kilning, this water content is reduced to 5–10% moisture over a period of roughly 24–48 hours. In Munich malting, the moist air is recirculated in the kiln, helping to accelerate the production of amino acids and reducing sugars that will subsequently form coloring compounds through Maillard reactions. As the moisture content is reduced, the maltster increases the temperature until it reaches 100°C, and it is held at this temperature for as long as 5 hours. The combination of a long drying phase at a low temperature and a high kiln-off temperature is essential to creating Munich malts. At lower temperatures, the malt dries and forms abundant amino acids and reducing sugars. At higher temperatures, the Maillard reactions are favored. The chemical changes that occur during this stewing/kilning process — including the production of melanoidins — are essential to the nutty/malty/bready/toffee characteristics that Munich malt imparts to beer. In Munich malt, melanoidins are the result of specific manipulations of malting conditions. Melanoidins are one product of a general reaction (Maillard reactions) between a reducing sugar and amino acids. A related chemical reaction to melanoidin formation is called Strecker degradation. Like the classic Maillard reactions, Strecker degradation involves an amino acid such as leucine or valine reacting with a reducing sugar to form an aldehyde and a Strecker aldehyde, mainly during the malting process. Strecker aldehydes such as isovaleraldehyde tend to impart flavors described as biscuity or malty. These aldehydes can remain unchanged and be carried over into the finished beer or react with additional reducing sugars to produce melanoidins.
The predominant flavor compounds present in Munich malts are furans, pyrroles, and Strecker aldehydes. Although the chemistry and names may seem complicated, the compounds created are essential to imparting what many brewers describe as classic malty and bready aromas and flavors to beer. The reactions that produce the flavors and aromas desired in intensely malty beers are mostly the work of the maltster. The fact that the vast majority of the melanoidins in a malty beer can be extracted through mashing with Munich malt is a blessing for brewers. All the brewer needs to do is determine the correct proportion of the malt to use in a given recipe to yield the desired effects. While a certain degree of confidence can be placed on buying good European floor-malted malts, experimentation is a good idea in selecting Munich malts.
Recipe formulation: Although each brewer will make judgments based on his or her own tastes, typically 5–10% Munich malt contributes plenty of character to most ales. Lagers, on the other hand, may require much larger percentages, especially if the intent is to brew characterful Bavarian Dunkels or Bocks. Several authors have proposed using Munich malt as the majority of the grist for Bocks and particularly Doppelbocks. This approach, combined with decoction mashing, results in very distinctive and full-flavored lagers.
Mashing procedures: The one area that you should be concerned with is careful mashing procedures that minimize oxygen pickup. Although this warning is generally true for all mashing, it is particularly important when working with Munich malts. Melanoidins in their reduced (unoxidized) state provide excellent flavor stability by serving as antioxidants. Oxidized melanoidins, however, are blamed for some particularly unpleasant flavors and rapid deterioration in packaged beer. This is especially significant to craft brewers who bottle their beer and ship it over great distances.
Enzyme activity: Despite the fact that Munich malt is kilned off at around 100°C, the long, gradual process that leads up to this temperature is the key to Munich malt’s enzymatic profile. A typical pils malt may have a diastatic power (rating of enzyme activity — the higher the number the more the enzymes) of 105 degrees Lintner (dL); Munich malt is usually around 50 dL. This diastatic power rating may seem small relative to pils malt, but it is plenty to convert the starch present in the malt. It may be insufficient to convert a significant amount of starch from adjuncts, but a typical beer made with Munich malts would not normally use a high quantity of adjuncts but would instead use standard malts of high enzymatic power.
Munich malt compared to Aromatic malt: Aromatic malt is a specialty malt from Belgium that is in many ways similar to Munich malts, but in other ways it is closer to caramel malt. Like Munich malt, aromatic malt undergoes the same low-temperature kilning procedure of drying and liberating amino acids and reducing sugars. The difference arises in the kiln-off temperature; in aromatic malt production, the final kiln-off is at 115 °C, resulting in a darker malt of 20–25 °SRM; the diastatic power, however, drops to 30 dL. Aromatic malts are useful in some recipes, but with its lower enzyme content and much higher coloring potential it is best kept to proportions below 20% of the grist.
Munich malt is a powerful tool that brewers can use to produce classic malty continental lagers and robust ales. High-quality Munich malts, in particular those produced in classic European floor makings, are sure to add a distinctive malty/nutty/biscuity contribution to the finished beer. The fact that Munich malts retain a moderate degree of diastatic enzyme activity allows brewers to use this malt at any percentage they desire.
Munich is widely considered a malt that can substitute for traditional pale malt. Professional brewers, however, would advise its use in moderation, as its enzymatic power is low. Munich works well for bringing a deep orange color and a malty, grainy flavor to your brew. Munich malt has a color rating of 5–20 degrees Lovibond (°L), depending upon its origin. For comparison, English 2-row malt is rated at about 3 °L. The higher-rated Munich offers rich orange hues in finished beer, which can be good for amber or darker beers, like Märzens or Oktoberfests. The flavor Munich offers tends to be a deep, malty, grainy flavor that may also be described as slightly toasty in some cases. Munich malt can be used as a primary malt, but — because of its low diastatic power — it’s not really recommended. Munich malt has a lower enzyme concentration and cannot be relied on to convert starch from enzyme-deficient adjuncts and special malts.
Munich malt is rich, malty, biscuit-like and intense. Color ranges between 8-25 °L. Lighter Munich malt can be used to a greater percentage because there’s enough diastatic power to compensate for less base malt. Dark Munich, however, is so limited in diastatic power as to relegate it to the category of a specialty malt. For standard Munich (10 °L), use 10–30% of the grist for dark beers and bocks, 5–15% for ambers and Märzens, 3–7% for pale beers and Canadian lagers, and 2–5% in low gravity brews. 
Typical Colour: 4 L, 6-9 EBC
Common Brands, Variations: Weyermann Vienna Malt, Gladfield Vienna Malt
The production methods of Munich and Vienna malts are similar, except that Munich malt is kilned longer. Vienna malt is lighter and sweeter than Munich malt and is a principal ingredient of Bock beers. Retains enough enzymatic power to convert itself but is often used with a base malt in the mash. 
Vienna Malt is a kiln-dried barley malt darker than pale ale malt, but not as dark as Munich Malt. It imparts a golden to orange color and a distinctive toast or biscuit malt aroma to the beer. While it is now considered a high-kilned malt, Vienna malt was one of the earliest pale malts and formed the basis for a breed of lighter lagers exemplified by Vienna Lager. Vienna malt traditionally makes up up to 100% of the grist of Vienna Lager and the bulk of the related Märzen style. Other beer styles sometimes use Vienna malt to add malty complexity and light toasty notes to lighter base malts, or to lighten the grist of a beer brewed with mostly Munich malt. Examples include Baltic Porter, Dunkelweizen, and most styles of Bock. 
Vienna malt has a high diastatic power and works well as a base malt. Although, like Munich malt, it is also kilned at higher temperatures, Vienna malt is not subjected to the heat as long, which enables the activity of the enzymes to be high and strong. Vienna malt offers a grainy, malty flavor, but is much less pronounced than that of Munich malt. It has a color rating of 3–5 °L, making it comparable to English pale malt. It works very well with the heavily-hopped beers because it adds a great degree of malt character without overshadowing the highlighted hops. Due to its light color offering, Vienna is a versatile malt. You can sneak 25% into a Bohemian-style Pilsner for additional malt chewiness or use 90% in an amber. Can be used as a partner to pale ale malt, in small percentages (3–5%), for a bit more richness in the malt profile. Vienna has a place in many more beer styles than you may have first thought. Use 10–30% Vienna malt with Pilsner beer to add color and malty flavor. Use 60–90% Vienna malt for light-colored amber beers, together with caramel malt. Use 70–80% Vienna malt for medium-colored amber beer, along with caramel malt. 
Typical Colour: 3 L
Common Brands, Variations: Weyermann Melanoidin Malt
This malt will add red coloring and intensify the malt character of your beer. Used in a wide range of styles: Amber and Dark lagers, Scottish Ales, amber ales, bocks and doppelbocks.
Melanoidin Malt is very aromatic with intense malty flavour. Gives fullness and roundness to the beer colour, improves flavour stability and promotes red colour in the beer. Gives beer fuller body. Has been described as “turbo Munich”.
Carapils (aka Dextrin Malt)
Typical Colour: 3 L
Common Brands, Variations: Weyermann Carapils/Carafoam, Briess Carapils, Gladfield Gladiator Malt
This malt is used sparingly and contributes little color but enhances the mouthfeel and perceived body of the beer. A common amount for a five gallon batch is 1/2 lb. Dextrin malt has no diastatic power. It must be mashed; if steeped it will contribute a lot of unconverted starch and cause starch haze.
Caramelized malts are any malt that the maltster mashes in the kernel. This step is known as “stewing” or saccharification. The maltster takes malt without crushing it and hydrates it. He then heats the water-malt mixture to a mash temperature of 140° to 160° F. The malt is held at this temperature for 1 to 2 hours with minimal ventilation. This causes the malt enzymes to degrade the starch in the kernel, thus effectively mashing each individual kernel. Most but not all of the starch is degraded to small sugars. Most caramel malts are made in roasting drums where ventilation and temperature are easily controlled. Stewing allows the starch inside of the malt kernel to convert to sugar, just like mashing.
After the stewing step, the malt is then dried and roasted at various temperatures and times. The maltster dries the mashed malt kernels at a given temperature from 180° to 350° F. This causes the sugars to crystallize. It also causes the sugars and nitrogen-based compounds (mostly amino acids and proteins) to combine to form melanoidins (brown to red color agents). The higher the drying temperature, the darker the color will be.
Malt kernels have an internal pH at this point of around 7. This pH is conducive to both caramelization and melanoidin formation. Both chemical reactions work better at higher pH.
Caramelization is the formation of brown color from the rearrangement of sugar molecules without the help of nitrogen-based molecules. Because caramelization occurs during this malting process, these malts are commonly referred to as caramel or caramelized malts. However, all caramelized malts have crystallized sugar in them, but not all crystallized malts have a large amount of caramelized products in them. Also, some specialty malts that are made without in-kernel mashing have caramelized products in them.
Caramel malts contain high concentrations of Maillard reaction products (“MRPs”). The Maillard reaction is a complex series of chemical reactions initiated when “reducing sugars” react with free amino nitrogen. This occurs in hot, moist environments. Reducing sugars include sugars like glucose and maltose that are formed when starch is broken down by amylase enzymes. The stewing step drastically increases the concentration of reducing sugars inside of the malt kernel. Free amino nitrogen refers to the nitrogen end of a protein or polypeptide not chemically tied up in a peptide bond (the bond between two amino acids in a protein or polypeptide chain).
The concentration of free amino nitrogen increases when barley is converted to malt. Well-modified malts have a higher concentration of free amino nitrogen (frequently called FAN) than poorly modified malts. When sugars participate in the Maillard reaction they become unfermentable; that’s why using a high proportion of crystal malt increases the final gravity of beer.
The Maillard reaction is responsible for the formation of a wide array of aromas including toffee, caramel, toasty, nutty, raisin-like and sherry. The reaction is also responsible for an increase in color.
Toasted bread is a classic example of the Maillard reaction and can be used to illustrate how the reaction can progress from subtle to very pronounced colors and flavors. Some crystal malts are very light in color and flavor and are made using kilning regimens (after stewing) similar to pale malts. Darker crystal malts are kilned at higher temperatures for longer periods of time after stewing. Maillard reaction products are also widely believed to improve mouthfeel as well as beer foam stability. 
These malts may be steeped or mashed.
Extra Light Crystal (aka Caramalt)
Typical Colour: 10 L, EBC 20-40
Common Brands, Variations: Thomas Fawcett Caramalt, Bairds Caramalt, Weyermann CaraHell,
This malt adds a light honey-like sweetness and some body to the finished beer.
Typical Colour: 20 – 40 L, EBC
Common Brands, Variations: Thomas Fawcett Pale Crystal Malt, Bairds Pale Crystal Malt, Weyermann CaraMunich I, Weyermann CaraRed, Gladfield Light Crystal Malt
The additional color and light caramel sweetness of this malt is perfect for pale ales and amber lagers.
Typical Colour: 50 – 60 L, EBC 90 – 160
Common Brands, Variations: Thomas Fawcett Crystal Malt, Bairds Medium Crystal, Weyermann CaraMunich (II, III)
This is the most commonly used caramel malt, also known as medium crystal. It is well suited for pale ales, English style bitters, porters and stouts. It adds a full caramel taste and body to the beer.
Typical Colour: 80 – 120 , EBC 170 – 230
Common Brands, Variations: Gladfield Dark Crystal Malt, Weyermann CaraAroma, Bairds Dark Crystal Malt,
This malt is used for making reddish colored beers and gives a bittersweet caramel flavor. Useful in small amounts to add complexity or in greater amounts for old ales, barleywines and doppelbocks.
These highly roasted malts contribute a coffee or burnt toast flavor to porters and stouts. Obviously these malts should be used in moderation. Some brewers recommend that they be added towards the end of the mash, claiming that this reduces the “acrid bite” that these malts can contribute. This practice does seem to produce a smoother beer for people brewing with “soft” or low bicarbonate water.
These malts may be steeped or mashed.
Typical Colour: 400L
Used in small amounts for brown ale and extensively in porters and stouts, this malt has a bittersweet chocolate flavor, pleasant roast character and contributes a deep ruby black color.
Black Patent Malt
Typical Colour: 580L
This is the blackest of the black. It must be used sparingly, generally less than a half pound per 5 gallons. It contributes a roasted charcoal flavor that can actually be quite unpleasant if used in excess. It is useful for contributing color and/or setting a “limit” on the sweetness of other beer styles using a lot of caramel malt; one or two ounces is useful for this purpose.
Typical Colour: 550L
This is not actually a malt, but highly roasted plain barley. It has a dry, distinct coffee taste and is the signature flavor of Stouts. It has less of a charcoal “bite” to it than does Black Patent.
Hybrid Crystal/Roasted Malts
Typical Colour: 220 – 340 L
Common Brands, Variations: Dingemans Special B, Briess Extra Special Malt
This malt has a roasted nutty-sweet flavor. Used in moderation (1/4-1/2 lb.), it is very good in brown ales, porter, and doppelbocks. Larger amounts, more than a half pound in a 5 gallon batch, will lend a plum-like flavor (which may be desired in a barleywine in small amounts).