[MotoSook]

Harbor Freight sells a Killawatt that measures throughput and duration for about $30, IIRC. I have one and it's a nice product. It shows voltage, current, consumption.

ETA: Here the product at Amazon.

http://www.amazon.com/P3-International-Kill-Electricity-Monitor/dp/B00009MDBU/sr=8-3/qid=1161332551?ie=UTF8&s=electronics

Related article: http://www.mymoneyblog.com/archives/2006/10/frugal-gadget-save-money-with-a-kill-a-watt-energy-meter.html

Couldn't find the Killawatt I have at HF, but here's a different one:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=65731