Blackle - Energy Saving Search616,825.858 Watt hours saved
Blackle saves energy because the screen is predominantly black. "Image displayed is primarily a function of the user's color settings and desktop graphics, as well as the color and size of open application windows; a given monitor requires more power to display a white (or light) screen than a black (or dark) screen."
Roberson et al, 2002In January 2007 a blog post titled
Black Google Would Save 750 Megawatt-hours a Year proposed the theory that a black version of the Google search engine would save a fair bit of energy due to the popularity of the search engine.