eTailor

When your screen is white, be it an empty word page, or the Google page, your computer consumes 74 watts, and when its black it consumes only 59 watts.

Mark Ontkush wrote an article about the energy saving that would be achieved if Google had a black screen, taking in account the huge number of page views, according to his calculations, 750 mega watts/hour per year would be saved.

In a response to this article Google created a black version of its search engine, called Blackle, with the exact same functions as the white version, but with a lower energy consumption.

Check it out: http://www.blackle.com