Givezilla is a company started by Richard Waldvogel in Longmont Colorado that helps nonprofits earn up to 10 percent of product sales made on their Web sites. They do this by helping nonprofits create specialized, no-cost storefronts -- little Amazons -- that allow visitors to purchase merchandise directly from a nonprofit's site. Underneath the covers the store is built and the cart created using the Amazon API. And because Amazon allows the gross proceeds from all Givezilla's nonprofit clients to be aggregated, it results in a higher net affiliate percentage flowing back to those organizations.
Now that's a good use of an API.