What is a good party activity that is cheap?!

Best Answer - Chosen by Voters

Sleep over? Going out for ice cream? There's not really much left...

Card games. A deck of cards is usually under 5.00 and most people usually know a couple of card games.
Charades can be fun and usual doesn't cost much if anything. Take time before hand to come up with movie or song titles ahead of time.
If you have some board games like Monopoly or Life you could play that. A board game can cost under 30.00 at wal-mart.
Turn on the radio and have a sing along. Get up and dance.

A sleepover
Maybe ice skating in a pond that safe of course :)
Going to the mall
Go sledding on a really steep hill!