PrestaShop

PrestaShop is an e-commerce solution which is free and open source. It supports payment gateways such as Google Checkout, Authorize.net, Skrill, PayPal and Payments Pro via API. The software, which is based on the Smartytemplate engine, is currently used by 100,000 shops worldwide.[1] PrestaShop was named the Best Open Source E-Commerce Application in the Packt 2010 Open Source Awards[2]and the Best Open Source Business Application in the 2011 Open Source Awards. The software makes extensive use of AJAX in the admin panel, while module blocks can be easily added to the store to provide extra functionality.
FEATURES

Product Displays
Site Management
S.E.O
Checkout
Shipping
Payments
Marketing
Customer Log-in
Translations
Security
Store Management
Product Management
Analytics and Reporting
Localization/Taxes