Tweet-a-Watt won 1st Place at the Greener Gadgets contest this year – it's an open source hack that takes the data from a Kill-a-Watt and publishes via social networking site, Twitter. The device aims to make not only the user more aware of their energy use, but also your peers.
See it live here.
Have a twitter account and Kill-a-Watt monitor? Sign up to Tweet-a-Watt here.