So I went to Olinde's last week and bought a new mattress set, and I don't know what to do with the old one.

I know that people say that if your mattress is older than 8, it's time to replace it.  So what do I do with it?  Do I just bring it to the landfill?  Is there a non-profit agency that will take it? It comes with a (low-profile) box spring.

I figured that I'd ask you, because you always seem to have the answers.  HELP!