Oz Lubling: one of the best photography galleries in new york. They always put on great, provocative exhibitions. There's also an amazing collections of photo books.
Samuel B: Phenomenal gallery space known for boundary pushing conceptual installation exhibits. Highly recommended for fans of Art in non-traditional mediums.
IrmaZandl ZandlSlant: Great retail/gallery concept with a good collection of affordable art along with an Aesop store and a tatterly store. Make sure you check out the gallery "house" next door.