If you're interested in how much energy your electronics use, it's hard to find a device better than a Kill A Watt—except maybe the Kill A Watt EZ! P3 International now offers model P4600, which provides the same features as its predecessor, but it also automatically calculates device cost per day, week, month or year.

(Photo from http://p3international.com)

P3's new version does automatic calculation, and it also has a battery-powered memory to retain measurements even when unplugged. We still recommend using a short extension cord, because it's often difficult to read the Kill-A-Watt when it's plugged in to the wall. We recommend checking devices you suspect of high usage, and also those you don't. A laser printer, for example, uses very little power when idle, but things like an electronic pet-containment fence or even a doorbell can use much more than you'd suspect. Visit http://p3international.com/products/p4460.html for more information.