Does anyone know of a restaurant which delivers all night long - specifically, to downtown NY?

Downtown you may have a problem. Stage Deli in Midtown delivers 24 hours.

Blue Ribbon Bakery is open very late, so if the order is big enough, they might deliver.

Insomniac:
Can you be more specific? Downtown NY ( I ASSUME you mean Manhattan) is considered 14th St and below. Where exactly are you? A hotel? Apartment? Office building? If you are going to be in a hotel, the front desk is sure to have all the local places that will deliver. In anycase, you need to be more specific in order to get responses.

Considering where exactly you are asking for delivery from (or willing to travel), Wo Hop on 17 Mott is a 24-hour Chinese restaurant. Worth the hike if you are willing to venture outdoors.

I did mean downtown Manhattan, specifically Soho (apartment).
Thank you for your responses.

Sherwoods Fine Foods in midtown delivers 24 hours but again, probably not to downtown.