Check out Blackle.com. It's a search engine, powered by Google, but with one small, but possibly important difference: a black background. Black computer screens take less energy than white screens, and so having blackle.com as your homepage or standard search engine could eventually mean energy savings, especially if everyone who uses google switches over. They also have some tips for easy ways to save energy in your home and car, so check out their tips page.
You can't help but wonder... if the site is powered by Google, why doesn't Google.com just switch to a black background?