If you would have moved to Alexandria a year ago, you might have been able to go to Metro or V Street where there were some crucial street races on the weekends......cops cracked down on that though. Manassas on Saturday nights, Chic-Fil-A in Chantilly and Sterling has some gatherings on the weekends. As far as shops:
Inline in Springfield
CDE in Fairfax
Vertex in Tysons
Ultimate in Sterling
Welcome to NOVA.