popular e-commerce applications

Below are few most popular build-in ecommerce applications:

osCommerce
osCommerce stands for open source commerce is an open source ecommerce and online store management application 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. It can be used on any web server that has PHP web scripting language and the fast MySQL database. With no special requirements, osCommerce is able to run on any PHP 4.1+ enabled web server running on Linux, Solaris, BSD, Mac OS X, and Microsoft Windows environments. Availability of free contributions, forums have made it more popular and easy to implement.
Cube Cart
CubeCart is a powerful eCommerce script written with PHP & MySQL. With CubeCart you can setup a powerful online store as long as you have hosting supporting PHP and one MySQL database. CubeCart is not open source software and may not be redistributed.
VirtueMart
VirtueMart is an Open Source E-Commerce solution to be used together with a Content Management System (CMS) called Joomla! (but also works with Mambo). Joomla and VirtueMart are written in PHP and made for easy use in a PHP / MySQL environment. X-Cart: X-Cart shopping cart software is based on PHP Smarty templates, this makes it very flexible and easy to modify. The data is stored in MySQL database. This is not free.
LiteCommerce
LiteCommerce is a lightweight high-tech ecommerce solution devoted to make an internet store launching process as easy as surfing the Web. LiteCommerce is more than just a shopping cart. It is a multipurpose ecommerce store platform. Numerous built-in features will make your online store and your business successful: inventory management, credit card processing, SEO tools, special offers, discount coupons and others. This is not a free ecommerce application.
Zen Cart
Zen cart is a free open source shopping cart system developed in PHP/mysql. The ecommerce website design program is being developed by group of like-minded shop owners, programmers, designers, and consultants that think ecommerce web design could be and should be done differently.
Creloaded
Creloaded is a free open source shopping cart system developed in PHP/mysql. IT is a part of oscommerce with added functionality. It is free as well paid.