Last night Margo and I checked out the sushi restaurant Saki in Adams Morgan (2477 18th St).
We ordered a great deal of sushi, and even desert. Both the sushi rolls and the nigiri were good. And until 7:30 they have happy-hour prices which are pretty unbeatable, especially given the restarant's modern ambience and prime location.
The only downside seems to be the service. When you enter the first-floor sushi bar, the service seems to be fine on the right side... but the further down the bar you sit, the poorer the service becomes. Be forwarned.
Nevertheless, the place serves excellent sushi and has a great atmosphere, so I reccomend it! (They also have a good sized menu of non-sushi Japanese items for those squeemish of raw fish).