Our API directory now includes 116 retail APIs. The newest is the Leaf API. The most popular, in terms of mashups, is the Shopping.com API. We list 60 Shopping.com mashups. Below you'll find some more stats from the directory, including the entire list of retail APIs.
Violet this week announced what it says is a "unified API for anything on the internet." The idea is to make it easy for people to buy whatever they want, no matter where they see it on the web, without requiring them to backtrack or hop through ecommerce sites across the internet.