For those fans of virtualization (and running VMs for development) you're not stranger to VirtualBox. Over on the Google Code site, there's a project that wants to make it easier to work with your VirtualBox instances via a PHP-driven interface.
An open source, AJAX implementation of the VirtualBox user interface written in PHP. As a modern web interface, it allows you to access and control remote VirtualBox instances. Much of its verbage and some of its code is based on the (inactive) vboxweb project. phpVirtualBox was designed to allow users to administer VirtualBox in a headless environment - mirroring the VirtualBox GUI through its web interface.
The tool isn't designed to be a management tool for a "hosting" type of environment, but rather to help you admin all of your VMs at once (no "ownership"). It uses the SOAP service (vboxwebsrv) that comes with VirtualBox servers to create a clean interface.