I was out at Market Square here in SLC a couple months ago (if you haven't been there, its an experience for sure, 1600 Empire Road) and saw these packages of 100 coasters for .99 --I didn't know what I was going to do with them, but I brought them home anyway.
I'm still thinking about other uses for them, but for now, I just made them cuter :)
I used gray spray primer on one side, then a couple coats of chalkboard paint.
On the other side I used spray adhesive to attach some leftover scrapbook paper.
So, not a particularly revolutionary use, they'll come in handy for a summer BBQ, but I suppose they could be mini-chalkboards to keep kids entertained.