Quick heads up:
I created the Mid-Atlantic single speed (MASS) list for coordination of fixed gear and single speed group rides in the MD/DC/VA area since a lot of us locals shoot email back and forth all the time organizing these things. Thought this might make things easier and cut down on some of the email while doing some cross-pollination between people who know people who know people...
There's a calendar to post rides to as well as the general message list. You should be able to view both without actually joining if you aren't into that sort of thing.
Open to single speed and fixed gear rides, for sale items, etc.