Power managment for desktop PC's is something that has been around a while. Turns out that there are now several companies providing software that helps you to reduce power usage when your computers are not in use. Power wise, a well managed computer can save between 25 and 75 dollars per year according to the EPA. I know, I know, it's nothing. Read my earlier posts.
The piece by Madison Gas and Electric reviews almost every package out there. Looks like Surveyor, by Verdiem seems to be the best of the bunch, I think it's about 20 dollars per machine. Others include Nightwatchman and two free tools for the EPA, EzSave and EzGPO. Really, there is really no reason not to do this. Read the great case studies at the EPA site.