While we haven’t tried it ourselves, we’ve had reports from several users that iStat Server can be run on AppleTVs. Cool!
aTV Flash Forum: Instructions for installing iStat on AppleTV
Please note that we probably can’t assist you to get iStat Server up and running on your AppleTV as we haven’t done it ourselves.
Disclaimer: Hacking your AppleTV is risky. Bjango can’t be held responsible for any damage done to your AppleTV.