Now that everyone knows what a malt lover I am, I thought it would be appropriate to briefly mention decoction mashing, since it is a really good way to bring out the malt's full flavor and a lot of people are not that familiar with the process. Basically, it is the same as a step mash, except that instead of using hot water to bring your mash up to the next step you actually remove part of the mash (mostly grain with just enough fluid to give it an "oatmeal" type consistancy) and boil it. Then you add the hot grains back into the mash tun, which causes the desired temperature rise. I love decoction mashing for many reasons. For the amazing flavor it produces, the improved mash efficiency, and also the added benefit of not having to worry about overfilling my relatively small 5-gallon mash tun, since no water needs to be added for step mashes, or at mash-out (this is especially good when using larger amounts of grain for higher gravity beers). Here is an example of a decoction boiling away on my stove, the grain's rich, luscious flavors being extracted and concentrated right before my eyes!
You can perform one decoction to achieve mash-out temperature, or you can perform 2, 3, or even more to step from acid rest to protein rest to sacharification, and so on. The more decoctions you do, the more malt flavor you will produce! However, I have found that doing lots of decoctions makes the beer darker than expected and evaporates much more water, so you must take this into account when preparing your recipe. Personally, I love decoctions so much, that now I basically perform a short one (15 minute boil or less) at mash-out for 90% of the beers I make! It gives me a little bump in flavor, and makes my mashes a tad more efficient (my mashes are all well over 80% efficient using this method).
Now that I have malted my own barley (see my previous post), I will definitely be using a multiple decoction when brewing with those grains - I really want to get the most flavor out of my homemade malt!
So I won't go into all the details of decoction mashing "how-to's" because there's already lots of really good links out there with information. My favorite one so far is www.strandbrewers.org/techinfo/decoct2.htm. Check it out! It is really informative and even includes a graph that will allow you to figure out how much of your mash needs to be boiled to achieve the temperature change you are going for. Great stuff!