Stumbled upon this today. I think this is an awesome project!
It's easy, fast and free so please join! :)
“My blog is carbon neutral” is an initiative, originally started in Germany by the “Make it green” programme, that has the goal to reduce carbon dioxide emissions. We plant a tree for your blog and thereby neutralise your blog’s carbon footprint for the next 50 years! Everyone can make a small contribution to the environment. Every tree counts!