The Gaiam Community store has a great list of ways to reuse your yoga mats. Here are some of their ideas:

* Donate to homeless shelters as sleeping pads
* Use an exacto-knife to cut out shapes, letters, numbers, etc. Perfect for little fingers
* Line kitchen shelves
* Cut the mat into squares and use them as “bases” while playing baseball with the kids
* Cut into strips and use for drainage in flower pots

See the rest of the list here.