Electricity Usage Monitor
The electronics and appliances in our homes account for about 20 percent of personal energy use, according to the U.S. Department of Energy [source: U.S. Department of Energy]. But some gadgets can put a bigger drag on your electric bill than others, and nearly all continue drawing power even after they're turned off, a phenomenon known as standby power usage (or "vampire power," one of its more colorful nicknames).
If you want to find out which appliances are driving up your energy bill, you should consider buying an electricity usage monitor. After plugging a 120-volt alternating current (AC) appliance into the monitor and then plugging the monitor into the wall, the device provides data on how many kilowatt hours (or kWh, the unit of energy that electric companies use to determine your bill) you're using in a given time span. Some models allow users to enter their cost-per-kilowatt-hour to find out how much money they're spending. There is even an open-source device called the Tweet-a-watt that uses data from your monitor to make Twitter updates about how much energy your appliances use [source: Ganapati].