This EnerJar entrant won the recent Core77 Greener Gadgets Award for 2008. It’s an easy build DIY device to measure how much power you’re using. Nice idea, and something we’re probably going to need a lot more of as time passes and oil peakses.
The EnerJar is an easy-to-build, DIY device that accurately measures the power draw of electrical appliances. Sitting between any wall outlet and the appliance (think blowdryer versus laptop), the EnerJar helps users gain an understanding of power draw, investing them in the knowlege, and leading them to reduce their electricity use.