This isn't normal Businesspundit fare, but it's such a cool product I have to link to it.
The Kill-A-Watt plugs into a wall outlet and will measure the actual electricity usage of any appliance. I've been wanting one of these things for years, to the point of seriously considering manufacturing one myself. I'm glad someone has finally done it for me. It looks like my computer costs me something like $216 a year to run. Trouble is, I have five of them. Something's gotta go.