Chana, over at The Curious Jew, is trying to put together a guide to New York for Jewish Out-of-Towners (you mean there is civilization beyond the Hudson?).
Despite being an almost life-long New York, I'm not certain that I really understand Jewish New York (does anyone, really?). Nonetheless, I've added my two cents. Please head over there and add your experiences, insider tips and whatever else you think might be useful.