Kramers. I spent many an evening falling in love with books and their covers in this 24-hour bookstore/eatery/hotspot. Wish I had taken pictures of the interior, but if you've ever been it hasn't changed at all.
Ben's Chili Bowl. I lived in D.C. for three years before grad school and never ate there (and I know the owner's son, sort of!). But we made up for that with breakfast, complete a chili dog on the side. Yum!
Busboys and Poets. Another restaurant/bookstore/hotspot that truly impressed me. What a wonderful place to come to if you want to buy a book, get a quick cup of coffee, or hear great poetry. It truly is a neighborhood gathering spot.