July's Popular Science "kit of the month" features plans to build a Tweet-A-Watt. The Tweet-A-Watt is a great idea, but very limited in scope. If you remember my post on the Kill-A-Watt you know that this devices measures individual circuits. So it can measure your toaster, refrigerator, TV, or even a power strip with several appliances plugged in. But the Kill-A-Watt cant measure your AC unit or your Washer/Dryer - devices that usually use 220 Volts.
In order to see the big picture, you need a whole home energy monitor, like the TED 5000. This measures how much power your whole house is using, and not just a single circuit. Energy Circle is helping users measure their whole house consumption and display that data over Twitter with an older version of The Energy Detective (TED). Something that in my opinion is much more valuable than Tweet-A-Watt.
I'm not trying to discredit what Tweet-A-Watt has done, it is a pretty cool application, but to spend $90 dollars on a kit that will only display one circuit (this doesn't include the $20-$30 you'll spend on the Kill-A-Watt) is a little pricey. I would rather save another $110, buy a TED, and display my whole home's consumption.