Citrix Provisioning Server
This post links to a fantastic YouTube video of "Ardence" in action. In action meaning that 1 server is streaming 1 OS image, real-time to 500 desktops then rebooting into a different OS. Since this was so sweet, Citrix bought Ardence and renamed it Citrix Provisioning Server. Since then I've had the pleasure of creating some really cool PVS servers and trained IT on creating images and image management.