NYC's power grid is always flexing under varying loads and prices. What's insane is that no one's tried to game that data to live green while saving a few bucks.
This Ambient device uses that same data, glowing red when its time to power down, going green when juice is plentiful. Play along and power down that PS3 during peak usage and they'll even kick a few bucks down to you. I'm not sure there's a downside, other than it could turn your light switches into an OCD game of red light, green light 1-2-3. (Think hypermilling a Prius for max efficiency, except in your house.)
For now, only in NYC.
Home Joule [Joe Brown at WIRED Fetish]
Photo Courtesy of Wired Magazine