It's pretty well known that electrical power is at the core of a geek's existence. It breathes life into our entertainment, hobbies, our work and probably a lot of other stuff too. But getting a good grasp on how much power various devices consume can be somewhat difficult to reckon.

The Kill-A-Watt allows you to connect your appliances 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.

Also has these great features.

Enables cost forecasting Accurate to within 0.2% Cumulative killowatt-hour monitor Displays Volts, Amps, Watts, Hz, VA, KWH, Power Factor Operating voltage: 115 VAC Max current: 15 A Max power: 1875 VA Dimensions: 5 1/8" X 1 5/8" X 2 3/8" Also see Watt's Up which records data on power consumption