I've been getting scads of CES pitches from smarthome software and gear makers, and not a single one is as interesting as LiquidIce's Wii-home hack. It uses the Wii browser, a Flash interface and some PHP script to control the lights, thermostat, security camera, cable DVR, and stereo system. This script can be used with lots of devices, but the addition of the Wii Remote led me (and the creator of this system) to the next obvious iteration:
Another hack I am working on... would be to just pick up the wii-mote, select a light (by using a combination of LED's on the wiimote to show which light is selected) then hold A and wave the wii-mote up to dim the lights up, and wave it down to dim the lights down.
Plus, it would give me an excuse for carrying my wiimote around the house all the time.