Street markets are always fun. Nearly every weekend during the summer months a street or avenue is closed off for the markets. Just beware if you're driving, you will be directed all the way up or downtown in NY traffic which is always at a standstill in these areas.
If you plan on a visit to NY and want to find out more here are a couple of links.
Stop by at Unknown Mami's for a tour of the world, city by city.