Today my daughters and I found a plastic bag filled with old dirty crayons. Instead of throwing them away, we remade them. Here's how we did it:
1. Remove the paper from the crayons, and use a knife to scrape away the dirty parts of the crayon.
2. Break pieces of crayons into tiny paper (not wax paper) Dixie cups.
3. Microwave them a minute at a time, until they melt.
4. After they've hardened, tear of the paper.
I just sorry we didn't start doing this a long time ago. I thrown away hundreds of crayons over the years.