Just read a post that XBMC is now an application for a jailbroken Apple TV 2nd Gen. XBMC has been a favorite since I was able to install on my original (modded) xBox.
The installation requires a Jailbroken Apple TV 2nd Gen:
Jailbreak ATV G2 with Seas0npass
After that, just SSH to the box and 'apt-get' the XBMC application:
How to install XBMC on ATV G2
Now I can power my AppleTV back up and it will actually be useful for something other than Netflix!