Use this search engine, Ecocho!
When I’m bored and don’t have anything in particular to tend to, I use my StumbleUpon toolbar and find various interesting sites. I “stumbled” on a new search engine, but it’s not just a search engine. For every 1,000 searches done, they supposedly plant 2 trees! If it’s true than it’s a great thing, the little things truly do matter. So you should all start using it. I guess it uses Yahoo as it’s backend search engine.
Here’s the link: Ecocho Search Engine