Agent-Ohm

Agent-Ohm is a shopping cart platform focused on speed, extensibility and logical design.

The DesignTenets guide the changes done to Magento to bring it up-to-snuff with the larger PHP community's standards.

On the right you might see that the site claims the code license is "New BSD". Well, it's not. The code is under OSL v3, per the original Magento.
Why use Agent Ohm?

Well, for one, the bug tracker is open to browsing. The source code is open for browsing too... you can build your own plugins off of it and also stay current without having to jump through hoops to re-branch your SVN every release.

Secondly, if you're a developer, you want to have a nice, sensible programming API. I don't feel that a system driven by magic getters and setters provides the best API to outside developer