Avactis is a powerful PHP shopping cart application that has multiple versions (including free + open source) and impressive features.

It has everything and more to expect from an e-commerce tool on every level from product to member managements, orders and marketing.

Demo

A powerful yet easy to use E-commerce and Content Management System
seotoaster is easy for content writers, and website administrators featuring complete front-end edition.
seotoaster is easy for web designers requiring only 4 HTML template and 2 CSS to build a complete theme.
seotoaster requires a single core to power and revise multiple websites hosted on a same server.
seotoaster features a fully integrated shopping cart and complex sale or b2b Ecommerce quoting engine configurable in 60 seconds
seotoaster is truly the most advanced SEO CMS right out of the box, no plug-ins required; featuring automated 301 redirection creation, automated optimized on-site linking, automated link sculpting using JS, and even point and click link siloing. It also builds products pages using micro-formats, and web, news and product XML sitemaps
seotoaster is also the foundation for scalable successful web businesses; Build one, two and more websites, host them wherever you wish, then network them all to centralize your SEO and compound your marketing impact with a subscription to SEO Samba's SEO software.
seotoaster ships with a set of sexy themes ready to power your next project. Additional free websites themes are also available for download from our free websites themesstore.
seotoaster includes a plug-in system to extend it with functionalities

Screenshots

Shopping Cart Screens:

ReOS is an open source web based real estate listing portal management application.

Description:
Easy installation and configuration
Manage sales, rentals and holiday rentals or set up your own
Ability to define property types (Flat, Appartment, House, etc...)
Customers database
Multi-user / Sales agent
Each sales agent handles his property and customer data
Search by many criterias
Publish multilingual adverts auttomaticaly
Unlimited images by property
ReOS automatically creates image thumbnail for you
Upload multiple images at once to listings
Publish news and events with WYSIYG Editor
Contact form with automatic answer
Recommended properties section
Special offer section
Latest properties section
"Want to sell" section
"About us" section
Mortatge calculation
Mailing list to send newsletters
Holiday Rentals
Booking Management
Price management by seasons (High, Medium, low,...)
Calendar Availability
Search by Availability
Set up of Equipment, Area activities, Avalaible services and other comments.
And all features of a property
Maps
Google Map location
Front page map view
Customers
Registration
Private Area
Manage properties and pictures
Contacts
Help Desk/Ticketing
Email Registration
Customer association 
Response Management

Demo:

Axis Commerce is an open source free eCommerce software built with PHP, MySQL, Ext JS and jQuery.

This powerful eCommerce software is bundled with many useful features including Ajax based admin user interface, one page checkout, flexible discount system, poll module, shipping / tax calculator and multiple stores management.

Demo