Energy conservation!!!
When your pc screen is all white (like a word page, for example), your computer comsuption is about 74 Watt. When it's all black, the average is about 54 Watt. Because of this, a few month ago, Mark Ontlush wrote an article about the amount of energy that could be saved if Google had a black background instead of white. Considering the high popularity of the website, according to Mark, the energy savings would be about 750 MW-Hour per year. Answering to this post, Google created a black version of it's search engine named Blackle.com ( http://blackle.com) , that works the exact same way as the original version but uses less power. Pass it on to friends, family and discussion list...let's all give our support to Blackle!!
Of course, since our site is popular too =D we'll also change background to black and save energy! SAVE THE EARTH
P.S. my start-up page for Internet Explorer is changed from Google to Blackle.com and Desktop background is now all black...