It don't got no fancy USB, but the "power angel" by seasonic <http://www.seasonicusa.com/power_angel.htm> is great for this. I have my desktop plus two 21" lcd monitors plus desk lamps and electronics lab gear all plugged into it; very illuminating to see what takes how much power. The monitors together equal the whole computer; a large stereo also plugged in takes hardly anything even at loud volumes; and you can even clearly see how a computationally intensive screen saver burns 30W !

Recommended.

Jesse

Nice device Jesse, but wont work for us Brits or most of the rest of Europe iirc

Chris

...and rather cheaper, if less iPoddockesque:

http://www.maplin.co.uk/Module.aspx?ModuleNo=38343&TabID=1&source=1&doy=24m7