Supervegan.com is definitely a great resource... there are too many places not to miss in NYC

Just to give you a highly subjective shortlist, I went last year and these were my highlights:
Upper East Side
http://www.candle79.com/ Expensive but very good. A couple of blocks away is Candle Cafe which is their cheaper sister restaurant
East Village
http://www.lulassweetapothecary.com/ Ice-cream parlour
http://www.atlascafe.net/ Non-veggie but vegan friendly, stocks many many vegan cakes and gets an AWESOME vegan doughnut delivery Tuesdays (late afternoons)
http://www.angelicakitchen.com/ Hippy food, pretty good tho
Lower East Side
http://www.babycakesnyc.com/ cupcakes galore... very good ones
https://www.teany.com/ Moby's wife's cafe - veggie
I also went to this museum in the area:
http://www.tenement.org/ which was a good peek at NY ghettos from 150 yrs ago
NB if you need falafel there is a Maoz in Times Square.
If you get time to venture out of Manhattan, the following in the Park Slope area of Brooklyn were also good:
http://www.urbanspoon.com/r/3/622375/re ... e-Brooklyn veggie cafe
http://dizzys.com/ non-veggie but good diner, which a lot of celebs take their kids to
http://www.caracasarepabar.com - non veggie but good tofu options