BV Commerce
Host your store on your own servers or with any web hosting company giving you the freedom and flexibility every business needs. BV Commerce has everything you need to create a store and process orders. Key Features: Search Engine Optimization, Built-in Templates and Unlimited Plug-ins, Create Rich Products without Programming, Image Swap When Choices Change (i.e size/color), Built for APS.NET 2.0 (not just recompiled), Full Source Code Included, Automatic URL Rewriting, Custom URL Rewriting, Ship directly through UPS and Print Labels.

CRE Loaded
Create your storefront catalog and upload product images, text, and graphics to your storefront. Manage orders and inventory with the shopping cart. Process credit card payments through PayPal or Authorize.net, set up special pricing, and determine shipping costs. And so much more -- and all from anywhere you can access the Internet. CRE Loaded also offers hundreds of different templates to customize the look of your online store, so you can offer your customers a unique, easily identifiable, and fully branded shopping experience.

CubeCart
CubeCart is an eCommerce script written with PHP and MySQL.

dashCommerce
dashCommerce is an ASP.NET Open Source e-Commerce Application. Built using some of the latest technologies, dashCommerce is focused on providing a robust e-commercce application that is stable and highly usable. In addition, the dashCommerce community is one of the most active communities in the open source / .NET space, so take a look around

Interspire Shopping Cart
Interspire Shopping Cart is e-commerce software that includes everything you need to start, run, promote and profit from your online store. It combines easy-to-customize store designs with marketing tools proven to significantly increase your sales.

Magento
Magento is a feature-rich, professional open-source eCommerce solution that offers merchants complete flexibility and control over the look, content, and functionality of their online store. Magento’s powerful marketing, search engine optimization and catalog-management tools give merchants the power to create ecommerce sites that are tailored to their unique business needs.

Miva Merchant
MIVA Merchant is a dynamic storefront system which enables merchants to create, enhance, and maintain an online storefront presence easily, all from their web browser.

osCommerce
osCommerce is an online shop solution that offers a wide range of out-of-the-box features that allows online stores to be setup fairly quickly with ease, and is available for free as an open source based solution released under the GNU General Public License.

Pinnacle Cart
Pinnacle Cart is feature rich shopping cart and website builder application designed to drive traffic and increase sales. FREE 15-Day Trial.

ZenCart
Zen Cart truly is the art of e-commerce. It is built for entrepreneurs by entrepreneurs. The program is built by programmers and designers who understand the online selling process from start to finish. Zen Cart has included all the necessary tools required to build a successful online store and we are constantly improving and upgrading the software based on our users requirements.

VirtueMart
VirtueMart is an Open Source E-Commerce solution to be used together with a leading Content Management System (CMS) named Joomla.