If I'm driving in a new place, I'm confident that I'm the biggest jerk on the road, simply because I learned to drive in New York. I think that if you can drive in New York City, then you can take on the world. Driving through Times Square alone deserves some sort of special recognition.
The biggest difference I've noticed about driving in NYC versus driving in other states is how other motorists respond to emergency vehicles. Ever seen an ambulance trying to get down a busy street in Brooklyn? A nightmare. Even worse -- the Belt Parkway! No one lets the ambulance through and if it is let through, then other drivers are trying desperately to stay behind it.
Speaking of cab drivers (that's who I was thinking of in that last paragraph) -- I have no problems with other cab drivers in other states! They are friendly and courteous. They don't try to cut me off, honk at me before the light has even turned green, etc., etc.
And one more thing: drivers signaling their thanks. I make sure to give a little wave, stick my hand out of my window and give a thumbs up or put on my hazards briefly if someone lets me in or makes my time driving that much easier. My point is that I go out of my way to show my gratitude. This is NORMAL in other states. (You know what else is normal? Pedestrians without a ridiculous sense of entitlement!).
/end rant. :)