A new search provider is in town. I know, who needs a new one since we enjoy Google/Bing that much that we even use it as a verb.
This one is different. While Google and Bing have major coörporations behind them and bring in lots of revenue, Ecosia is a green search engine that donates at least 80% revenue to the green cause. By now they have generated over 800 000 euro for the Amazon Rainforest!
Ecosia is powered by Bing/Yahoo search.
Is it the only green search engine online? No, you also have Green Maven (powered by Google) that has a similar set of functions, but is more community based (read: you can add sites there) and is less clear about their goals and revenue, in my opinion.