Zen Cart
Zen Cart is an open source e-commerce application. Zen Cart forked from the osCommerce application in 2003.
Zen Cart truly is the art of e-commerce; free, user-friendly, open source shopping cart software. Zen Cart is developed by a group of like-minded shop owners, programmers, designers, and consultants that think ecommerce web design could be and should be done differently.
-Zen Cart developer