A girlfriend of mine just celebrated her 21st, and she rented a "Bang Bus." Basically, it's a bus that you can rent out that will drive you and however many of your friends to different places. She had a keg on the bus (don't know if that's legal), and everyone had a smashing time!! It looked like a lot of fun from the pictures. The bus was PACKED with all her friends.
OMG I hope they have a company that does that in my area!