I live in DC area, as well.
Advanced Helicopter Concepts has a 206, but I just got off the phone and it's not insured for training. They are based out of Frederick, MD and are probably the closest to D.C. (about 45 minutes north off I-270).
Jet Services out of Manassas has one and only one R22. They have purchased an R44, but it's not operational for training, yet.
Helicopter High has R22, R44, and 206. I just gave them a quick call, and their 206 isn't insured for flight training either.
There used to be an operation at DCA (Reagan-National), but they moved after the flight restrictions. I think they went out of business shortly after that because most of their clients were executives, congressman, and the like.
Good luck!