Mount Rainier Bike Coop, just over the Maryland line in Prince Georges County, a mere 4 miles up Rhode Island Avenue from Logan Circle:

http://www.tfkmetrodc.org/mrbc.htm

I used to live in MR and volunteered at the coop there. Tell PJ that Juliellen sent you.

There used to be a bike coop in Shaw off of RI Ave at 12 NW, I think, but it moved and/or closed down. Perhaps it just moved. I can't remember the name of it.

Another good resource is Proteus Bikes in College Park, MD on Route 1. Jill, the owner, knows about all sorts of bike and community stuff going on. Tell Jill I say hi.