Customer service-focused Zappos intends to make public a feature of its Zappos API that allows customers to access order history. The feature is currently available in its official iPhone and iPad apps, though there is no timeline for when Zappos will make it available to its growing developer community.
The Invisiblehand API brings this cleverly named browser add-on focused on finding the lowest price for something that the user is shopping for to a wider audience. Constantly updating prices on millions of products from books to air fares, Invisiblehand stands out for its ability to learn about new products it hasn't seen before. The documentation indicates this is a RESTful API with JSON responses.