What to do with Dry Ice

Well, today my father found several large pieces of Dry Ice in an alleyway(Don't ask me what it was doing there, but my Dad just found it lying on the ground). He brought them home and now I have them at my disposal.

Tell me,
what are some cool things to do with Dry Ice?

You could always make a Dry Ice Bomb

If your having a party, it looks pretty cool to mix dry ice with regular ice in a beer tub (big container to put ice & bottles of beer in). Pretty cool effect as the dry ice 'fog' flows around the beer bottles and, hopefully, flows over the side.

If I remember right you bust off a few small peices and put em in a plastic soda bottle with a little water, screw the lid on tight get out the way. Whatever you do don't eat it.lol.