If you're into "skankin'" then definetly do Adams Morgan. It was a hotbed of punk rock back in the early 80s, and some of the vibe is still there. There's a record shop called "Crooked Beats" there which only sells punk, ska, raggea, and indie. The bars are pretty fun there, but Saturday nights can be total mayhem and perhaps too many people. Georgetown is also good, especially on M street and down by the waterfront.

And as was mentioned by the previous poster, do visit Brickskeller. It's a DC classic and a beer drinkers nirvana.