Sometimes the brats from the farmer's market are a little dry for my taste. So, I find it helpful to boil my brats in some beer. I used to go buy a tall-boy of Bud to boil my brats so as not to waste a good beer, but my thinking on this has changed. My partner feels that you should only cook with a wine you would drink. I've decided the same goes for beer.
For my beer brats, I like to use a dark or amber lager. The darker malt gives the brats a little bit of sweetness to seal in the flavors. For this particular boil, I used a Coney Island Human Blockhead. For me, almost no one makes a better lager than the Schmaltz Brewing Co. Well, them and Great Lakes Brewing, but that's the list for me. I usually toss in about 10-12 oz. of beer with some chopped onions and water. This left me enough beer to have with dinner. Then, I figure one could throw in whatever flavoring for the boil. I keep mine simple.
The boil takes maybe 10-15 minutes. Then you throw the brats on the grill. The result is a tasty, moist brat, best served on a bun with mustard.