It would be painfully boring to list all of them because really, who cares? Celebrity sightings are often exciting in the moment and then instantly forgettable. But my most memorable ones in NYC overall:
#1 Steve Buscemi. 9 PM on a Saturday night in Park Slope, Brooklyn. We make eye contact as we pass each other. He then walks up to a dark, closed Citibank and starts peering into its windows.
Honorable Mention: Mary-Kate Olsen, wearing torn white rags and sunglasses the size of dinner plates, dining outdoors in the West Village, eating what appeared to be baby food, sitting only with bodyguards.