Meskerem
Meskerem, web site, 2434 18th Street NW, Washington, DC, 202-462-4100 (Metro Trip Planner - opens in new window) [Washingtonian | WaPo | City Paper | food-plan | Don Rockwell | openlist | Yelp | Gayot]
The best known Ethiopian place in the area, but there is no longer any reason to go here.
Washington is very strong in the area of Ethiopian food, so most of the places are recommended. The less refined places tend to have spicier food, and I prefer those to Meskerem; you can pretty much pick one randomly. But Meskerem is where most of us started.