A really cool program that I have enjoyed for some time now is called RecycleBank
Just sign up and do various tasks such as recycle, take quizzes, learn about environmental issues, etc. and you earn points. It is very easy to earn enough points for some pretty cool rewards. For example, right now they have a back to school promo where you can quickly earn over 100 points. This is enough to get a few valuable rewards - $2 off a Kashi product or a free Oatmeal from McDonalds for example.
If you are lucky, your community's recycling program has joined forces and you can REALLY rack up the points quickly.
Check it out - it's a great way to earn neat rewards while helping out the environment!