I am really big into up-cycling. Using something I have or buying materials from thrift stores to make another item I'll actually use is really important to me. And its certainly a part of what the message Earth Day is working to get out; REUSE, Reduce, and Recycle being one of many ways you can make an impact.
A pre-school teacher, Rockstarcharmer, posted this Earth Day project on Craftster. She had her class take the papers off of old crayon bits and melted them into new crayons, not a new craft, but this batch are really neat-o mini Earths.