If you have small young children, they can get in on these to deals I found.
1st is the from a local-ish grocery store chain, H-E-B and the are giving a free T-shirt to each child who reads 10 books, and has their parents fill out and mail THIS form.
2nd Half Price books summer reading program, which awards each child with a $3 store certificate, for each full week they read 15 min/ day. Fill out HERE and get the PDF form and bring it in to your local Half Price Books
3rd Barnes and Nobles has a summer reading program, kids read 8 books, and log it and their favorite part of the story in a special "passprt" form. go HERE for the "passport" you need to fill out, and more details
keep an eye out at your local library or other places for other summer reading programs.