d.c. recommendations?

Hallo good people, With little planning, I've decided to head out to D.C. for a few days. Anyone have a recommendations for cool record stores, used bookstores, (vegetarian) places to eat, neat things to see, dens of sin, etc. aside from the obvious? Copy any responses to blockout31@aol.com if you could. I'll be there from tonight through Friday afternoon. Thanks! Nirav