More than ever, websites are seeking out revenue opportunities. And for services that provide value, customers are willing to pay. However, if creating an e-commerce system is too much distraction for your development team, try to get yourself in on the Chargify beta.
Our API directory now includes 180 finance APIs. The newest is the TTAGG Stock API. The most popular, in terms of mashups, is the PayPal API. We list 33 PayPal mashups. Below you'll find some more stats from the directory, including the entire list of finance APIs.