Forestle uses the Google search algorithm, but the ad revenues associated with each search go to prevent deforestation (via donations to the Nature Conservancy).
According to the site, the average search saves about 0.1 square meter (0.11 sq. yd) of rainforest – approximately the surface of your computer screen. And Forestle’s browser plugins make altruism about as easy as possible. (Its creators estimate that about 5% of revenues will go to admin costs).
Here’s the interface – it’s minimalist just like the real Google, and has most of the same functions:
Via ars technica