Rumba Café, web site, 2443 18th Street NW, Adams Morgan, Washington, DC, 202-588-5501 (Metro Trip Planner - opens in new window) [WaPo | MenuPages | City Paper | openlist | Yelp]
A mix of Colombian and Puerto Rican dishes, with some other Pan-Latin elements thrown in. I have yet to go. Lots of arepas. Lots of mofongos (mashed plantains and garlic). It looks interesting.
Montserrat, Glebe Road, Arlington, VA, between Rt. 50 and I-66.
I went once and found the meat too tough, though the red beans and rice were excellent. The place has potential, but still needed to work out some kinks.
Update May 26, 2006: A commenter says it is open and located at 85 North Glebe Road, Arlington, VA, just north of Rt. 50, across the street from the McDonalds.
Los Arrieros, 7926 Georgia Avenue, Silver Spring, MD, right at the DC border where the neighborhood turns dicey. (Metro Trip Planner - opens in new window) [Washingtonian | Yelp | Gayot]
They have Mexican dishes also, I have not yet been. I’ll go when you tell me to, otherwise not. I am still waiting. Washingtonian recommends the seafood soup.
Brasa Roja, aka Braza Roja, 9984 Main Street, Fairfax, VA, 703-385-8141, just east of downtown Fairfax, near Roberts Road, in the mall with Total Crafts. Another branch at 8215 Georgia Avenue, Silver Spring, MD, 301-495-0092 (Metro Trip Planner - opens in new window) [Yelp]
Excellent rotisserie chicken and steaks, especially for Fairfax. The best yucca of the chicken places. Plus they serve a variety of good Peruvian dishes. Mexican food here is better than in many places. It only pretends to be Colombian, more pan-Latin than anything. They have cute waitresses, and lots of cops come as customers.