Some of the best crab cakes I've ever had anywhere were in a really unlikely place in DC. The Hitching Post (200 Upshur St. NW 726-1511) is a soul food restaurant (of the "roadhouse" genre, with red vinyl decor, and lots of men wearing hats) located in an incongruously residential nabe (right across from the Old Soldiers Home, with beautiful old shade trees, etc).
They do all the usual southern stuff, at bargain prices (especially considering portion size; their fried chicken dinner--fantastic, by the way--could feed a large family). But there's a puzzle. Their menu includes extremely expensive crab cakes. I forget their exact price, but while most entrees are under $10-15, the crab cakes are well over $20. And they're worth every penny. They're huge, they're all crab, with just a microfilm of crust, flaky, moist, and brilliantly, greaselessly fried.
The juke box has all the best R&B tunes, this is really The Place. I'm amazed it's not better known.