A good sports bar we just found the other day is the Dominion Brewery. It's actually part of the Convention Center, at the corner of 9th and M Streets. They have a 133 oz. beer for $30, anything they have on tap, which is one of the best deals I've seen in DC in a while.
Rocket Bar is cool- it's at 714 7th St. It's right by the MCI Center, and there are a ton of bars and restaurants in that area. Their site is rocketbardc.com. Right near there is a place called RFD- Regional Food and Drink- and has one of the largest beer selections in the area. It's owned by the same people who own the Brickskellar which has the world's largest beer selection but is in a bit of an awkward area in DC- their site is thebrickskellar.com.
I don't eat too often in that area, but here are a couple ideas. A variety of places. There are a ton of Horns in the greater DC area, and so there'll probably be plenty of other good suggestions.
If you go out to Penn Quarter, which is centered on the Verizon Center, there's a myriad of places to choose from. Including a BBQ spot called Capital Q that actually flies in their sausage from South Side Market. I'm guessing that's not what you're looking for in DC.
Jaleo is pretty good. It's a tapas joint at 480 7th St. It's pretty moderate pricewise, and the portions are good for tapas. If you'd prefer more of a steak place, the District Chophouse is basically across the street. If you happen to go to a Wizards game and have a ticket stub, they do 2 for 1 beers the night of the game.
A place I've heard good things about but never been to is Matchbox, at 713 H St. It's a pizza/assorted entree place. It's moderately priced. My wife went there last week with friends and really liked it- she also says Ella's is good.
As far as ethnic places not in that exact area, one of my favorites in DC is Pasta Mia, at the corner of 18th and Columbia, slightly up Columbia. It's a tiny Italian place run by a couple from Sicily and Rome. Guy does all the cooking, no one else in the kitchen, and the woman runs the front of the house. They serve insane portions for between $13 and 17. The one downside is the place is tiny and they don't take reservations, so either get there right at 6:30 when it opens or be prepared to wait up to 45 minutes or so in line.
Pasta Mia is in an area called Adams Morgan, and there are a ton of bars and restaurants there, and a very cool mixed ethnic vibe. It's a can't miss area if you're in DC for several nights. It's great, but it gets a little overcrowded on weekends.
There are many Ethiopian restaurants in the area, including several very good ones. One of the most famous is Meskerem in Adams Morgan, which is very good. However, I prefer a place called Dukem, at 1114 U St. It is in a somewhat sketchier looking area, but the food is unreal and the service is great. It's only a few blocks from the U St./Cardozo metro stop.
Another good spot in that area is Ben's Chili Bowl. It's at 1213 U St. It's been family owned and operated since 1958. They serve hot dogs and hamburgers, etc. And chili, of course. If you're drinking in that area, it's a great way to cap off the night. Also good for hangover breakfast or lunch.
If none of these work, or you want some more ideas, Washingtonian magazine does a top 100 cheap eats list every year. There's a range of restaurants, all cheap and very good. A lot of the really good places are in the suburbs, but there's some in DC. You can find it here: