Here’s an interesting app that raises money for Leukemia & Lymphoma Research. Pledgeit allows users to sign up using their Facebook account and dare their friends into doing something. The incentive is that if the friend completes the challenge, then a specified amount of money will be donated to the charity.
An example of a dare would be to challenge a friend to run around campus in a Superman costume. Friends and family can also donate, which makes it harder for the person to back out of. You can also pledge to do something yourself and ask for donations if you successfully complete it.