Stumbleupon Saves The World

Stumbleupon is working to save the world by planting trees to reduce global warming and produce more clean air.

For every thumbs up by Stumbleupon Toolbar users, Stumbleupon will plant a tree. From their site: "During the campaign period StumbleUpon agrees to donate funds to the National Forest Foundation to plant trees for each "Thumbs-Up", up to a maximum donation of $25,000. The Campaign is being conducted by the National Forest Foundation for the following charitable purpose: to benefit the overall operation of The National Forest Foundation."

Already they've planted over 7.000 trees and all you need do to help them plant more is click on the word, Stumbleupon and give it a thumbs up.