Kill-a-Watt Electricity Usage Monitor from Amazon.com $28 USD.  Check your electronics for energy leaks. 

Product Description
Connect your appliances into the Kill A Watt, and assess how efficient they are. A large LCD display counts consumption by the Kilowatt-hour just like utility companies. You can figure out your electrical expenses by the hour, day, week, month, even an entire year. Monitor the quality of your power by displaying Voltage, Line Frequency, and Power Factor