From the Forums: Save Energy with Motion Detectors
Let's face it, one of the biggest energy wasters is lighting rooms or closets that no one is using. It is really easy to turn on a light, walk away, and forget it for hours. That's energy and money gone. One way to combat this is by using a motion detector to ensure that you only light a room when someone is in it.
In the forums we've got a new Home Automation HowTo tutorial on setting up a basic system (along with some advanced ideas as well).