I'll second Bikeline. Very cool manager/staff. He gave me bearings for my hub for free. I have a 1990 Raleigh, and wanted to get a new wheelset, and he recommended I go to Via Bicycle to have it fitted (concerns over my 127mm dropouts vs. 130mm hub). So, not only is it a cool place, they actually referred me to another shop. Granted, Via Bicycle isn't exactly competition, because they deal exclusively with vintage bikes.

In my neighborhood (Northwest), I've had good experience with Wissahickon Cyclery.