Over the weekend I saw a pattern for sale in the Keepsake Quilting book where the yo-yo's were stacked and made into a clown- type of character (the yo-yo's made his arms & legs). If you don't want to make them into a quilt or wearable, this was a cute little fellow. Here is a link to him.
http://www.keepsakequilting.com/KQShopping/partsview.asp?action=lookup&partno=6706&subject=&catpos=