Auctions are not new on the net. They have proven to be succesfull - just think about ebay for example. A new one on the net however is Limbo, where the lowest bid wins:

A Salt Lake City woman named Sondra Peterson who won a $35,000 hummer on a bid of $36.65.

You play using your cellphone. The downside of this ? Limbo states they will use your information for marketing purposes. I guess the money has to come from somewhere.

Link : Limbo