OsCommerce.com is an online shop e-commerce solution, aimed at offering a wide variety of out-of-the-box features, so that they can allow online stores to be setup quite quickly with no difficulty.
One of it main attractions is that it is offered for free as an Open Source based solution. They are currently powering 12,743 registered live shops worldwide. Their comprehensive online store solution contains not only a catalog frontend but also an administration tool backend which can be installed and configured easily over a web-based installation procedure. Their online shop program offers different features, such as order history, shopping carts, full search capability, product reviews, secure transactions and bestseller lists, among many others. If you want to view online demonstrations, just check out their demonstrations page. 
