Following on from the previous post on Earth Hour, if you get the chance, do take a look at The Age Of Stupid, a powerful new movie about climate change. It's currently being screened at a series of one-off showings at cinemas throughout the UK and the makers are hoping to generate enough interest to get it on general release. If you live in the UK, check here for a screening near you.
International screenings will follow. US release is scheduled for May, Australia for July, and India for September... You can also organize a screening yourself at your college, school, pub, bookshop, cinema, local group etc. See details of how to do this here.