go here: http://www.smarthome.com/powersave.html and look for "occupancy sensor". These replace the light's switch and can be set to turn on the lights when you come in, and turn them off if you leave the room. Also can be overridden to act as a regular switch. This site isn't the cheapest on the planet but I have had good luck with them and they have a good collection of "neat stuff". cheerio! ... Go SAS!