I have an extra rotary cutter that is marked "for paper only" and I save the used blades for cutting cardboard, poster board, paper, and when the husband needs something cut in the garage (like a mat or rug) I have them ready. You can also trade them in for new ones. The company will give you credit for each blade (like about $3.00) and you pay for a new one (much cheaper than some of the quilting companies) and you are recycling the blades. I will check my notes and see if I can find the url for everyone. Here it is:
http://www.lpsharp.com/