I recently discovered Freecycle (http://www.freecycle.org) and urge everyone to see if there is a group in your area. It is awesome! If you have anything to give away, you can post it... If you're looking for something, you can post it... and it's all FREE. Have something just sitting around the house that someone else might like?
I found a great website, http://www.answer4earth.com and it's basically the same idea as Free Rice, but it is about trees. For every 300 correctly answered questions, a tree gets planted. You do not have to answer 300 questions yourself, any bit helps, and it's multiple choice. A lot of fun!