In the market for antiques? My sister has an online store to go with her brick-and-mortar shop in San Antonio. She specializes in glass beads and jewelry, but also has vintage porcelain, paper, textiles, furniture, you name it.
As an example, one project is to create an application that will take your iPhoto albums and upload them to flickr as photo sets. Add a photo to an album and the software adds that photo to the flickr set.
If that idea interests you, you can donate some money to the cause via PayPal. When someone creates an application that meets the criteria, they claim all the money donated. If nobody creates the app, the money goes back to the donators.
Other examples include everything from finding a cure for breast cancer to funding a family vacation. Bounty Up takes 0.5% of the bounties on charitable bounties and 2% on other bounties.
I don't know if they'll be successful, but I thought it was an interesting idea.