Blackle.com boasts about how they save energy.
However I was watching a video (2:30 for the bit concerning my post) the other day with a professor showing how LCD screens work. That the backlit is always on and it works be varying the angle of the light from the backlight through polarised sheets. The varying the angle of the light is done by applying charge to some molecule or something.
The video says that to block the light passing through (to make the pixel black) a charge has to be applied. So surely if all the pixels have charges applied to them to make them black. Blackle is actaully using more energy than Google.