New York State Office of Unclaimed Funds
Nick Gaffney told me about this site, so credit/blame can go toward him.
Search for Lost Money
Nick managed to get some money through this. My experience is TBD. If they find some unclaimed money for you, they don't tell you how much you're getting; you just have to wait for it.
Worth checking out. It's endorsed by Nick Gaffney so it's gotta be legit!