Check out this Digg about Google.
A guy calculated something which is important to the whole world of computing *www.day.az/forum/style_emoticons/default/thinking.gif
From what it seems, an all-white web page uses about 74 watts to display, while an all-black page uses only 59 watts. Taking Google searchpage which gets about 200 million queries a day into account. Let's assume each query is displayed for about 10 seconds; that means Google is running for about 200000000*10/3600 = ~555,000 hours every day on some desktop in the world. Assuming that users run Google in full screen mode, the shift to a black background will save a total of 15 (74-59) watts. That turns into a global savings of 8.3 Megawatt-hours per day, or about 3000 Megawatt-hours a year.
Think of the power-savings if Google turned black!!!
Whatddya think?