Tree Nation, a non-profit based in Barcelona, Spain, is developing a cool web application to plant 8 million trees in Niger. The project is based on the premise that desertification is one of the most threatening ecosystem changes impacting the livelihood of the poor. You can purchase a tree, and select its planting location on a virtual map, and memorialize the tree through tagging and comments. The project will soon assign GPS code to each tree, so your tree can be found and viewed.