I get / give the wave 75% of the time in Boston. Had several stop and chat's through open windows in parking garages and at red lights. It's a still a great community, even if the 'novelty' is wearing off.
Younger teens don't seem to wave at all - they just want to throw down. In traffic on a number of occasions I've had a WRX or other Subie stop to let me merge / get in front. I return the favor whenever I can.
My wife get's challenged CONSTANTLY. Seems like everytime she drives she's telling me about some little noisy civic on the highway wound out in 3rd gear... Funny, as I don't really get messed with. Save it for the track.