When my children were younger I loved enrolling them in the summer reading programs.  Our local library has one each year and as my children have gotten older they have gone from enrolling in the program to helping out with the program.
It is such a great way to give them something educational to do during the summer.

*Check with your local library, they might have a great program
*Barnes & Noble - Receive a FREE book when you read 8
*Borders - Receive a FREE book when you read 10
*HEB - Receive a surprise when you read 10 books
*Chuck E Cheese - Read 2 weeks and receive 10 tokens

If you know of any other programs click on the title of this post and leave a comment.