My girlfriend would LOVE this gadget from Thinkgeek, called the Watt’s Up! She is paranoidal when it comes to electricity wastage. One step out of the room without turning off the lights and fans, she’ll start screaming at me. With this, she’ll have concrete prove to scream at me some more.
Simply plug any device into Watt’s Up and the meter instantaneously displays the wattage being used, as well as 15 other values, including average monthly cost. The device records this data into non-volatile memory (stored even if power is lost). One thousand twenty-three data points are stored, starting with a sampling rate resolution of one second. It records any power interruptions, which is extremely handy when performing an audit of several devices. Watt’s Up is also capable of real-time logging. It even includes a payback calculator software utility, which automatically calculates the time required for a new energy efficient appliance to pay for itself!
But seriously, US$130 seems rather steep.