Ah, the Brickskeller. You know that Sam Adams commercial where three guys walk into a bar and the hot blonde, slightly-looks-like-Buffy-the-Vampire-Slayer bartender thumps down a family Bible-sized menu of all the beers they serve? Yeah, that's the Brickskeller. Minus the vamp-chick leather and pretension.
Brickskeller actually is listed in the Guinness Book of World Records for "the most varieties of beer commercially available... has added 1,072 to the list since 1983." You name it, they've probably got it, and they're all listed by country on their menu, which, thankfully, is just the size of a small booklet, not "War and Peace."
A fun game we like to play is to theme our drinking rounds -- this round, we'll drink beer only from former Soviet-block countries, or this round, we'll drink from the Commonwealth, or from countries that begin with a vowel, etc. See, because you have to have some way to introduce order into the chaos.
In addition to ridiculous amounts of beer, Brickskeller also features a so-so wine list (but let's face it, you're not coming here for the wine) and has an excellent selection of single-malt Scotch.
Ambience is casual, like an old drinking club used to be. Get there early on the weekends, as this place gets crowded.
Metro: Dupont Circle (Red line)
Website: http://www.thebrickskeller.com/