I don't know if you're looking for a traditional fundraiser or some crazy new idea... but my fav traditional style fundraisers are:
Doughnuts:
http://www.krispykreme.com/Fundraising/How-It-Works
Coffee:
http://www.drivencoffee.com/fundraising
Candy/Chocolate:
http://www.hersheys.com/fundraising/
Good luck!