If you are a Google user like me and it's the search engine you are constantly using, you can help save energy by using Blackle. It saves energy because the screen is predominantly black. In 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.
I have set my home page to Blackle, as this would save a little bit of energy everytime I load my internet browser. It is a small step, but every bit counts. Visit http://www.blackle.com/about/
to know more about saving energy one search at a time, and help spread the word.