Black beans in my family, but we do it on new year's eve, not the day itself. It's a Latin American/Caribbean thing, I seem to recall.

OK, so Wikipedia has several mentions of traditions (Italy, Malta, Brazil, the U.S. South) in which some sort of bean is to be eaten on new year's day, or new year's night. Not one mentions new year's eve, so I've probably just misremembered. So, the big pot of black bean soup I took to a party last night probably didn't pack all the good luck juju I thought. Shame (tasted great anyway, though).