From Akkyra Systems:
Kilowatts is an easy-to-use tool for measuring your home electrical power use in real time. Kilowatts allows you to take precise measurements from the electric meter outside your home and gives you immediate feedback on your energy use.
The Kilowatts meter reader is a great tool to help you lower your utility bills and increase the energy efficiency of your home. See how much electricity is being used during different family activities. Find out what the energy wasters in your home are. Measure the energy savings from replacing or changing the settings on your appliances, installing compact fluorescent light bulbs or making other changes to your home.
Kilowatts does not require that you alter or even touch your electric meter. You simply need to time the rotation of the dial in the meter. (Please note that Kilowatts works only with a conventional electric meter with a rotating disc that indicates power use. It cannot be used with the newer, digital electrical meters.)
To set up Kilowatts to take accurate readings, just enter a single number that can be found printed on the front of your electric meter. Then measure your energy use anytime you wish with two taps on the screen of your iPhone or iPod Touch. Kilowatts reports the number of Watts of electrical power that your home is currently using.
If your electric meter has a number labeled "Kh" printed on it, you can use Kilowatts.
Kilowatts makes monitoring your home energy use easy!