E.M.
I actually found this on this site and used it at one of our bday parties. Put small toys, things like stickers, tattoos, etc, inside balloons and then blow them up. The kids have to sit on or otherwise pop the balloons to get the prizes out. We had 15 kids from 2 to 12, everyone loved it.
Scavenger hunt?
Put the Times Square celebration on TV and play spectator Bingo- make up Bingo cards with things like "Pink hat" or "NY Yankees logo" and have the kids watch the crowd for people wearing those items.
Disney trivial pursuit or Pictionary, Cranium Junior
Several jars of Play Dough or modeling clay to build your own Baby New Year