There are a few summer reading programs out there to encourage kids to keep on reading through the summer months. In return there are some fantabulous rewards for them. If you know of any, please feel free to comment and I will update the list. Thanks!
Chuck E. Cheese's - Read 2 weeks earn 10 free tokens. Seems to me that you could print the chart and use every 2 weeks of the summer if you wanted to. See here for the reading chart.
Siouxland Libraries - Read 20 minutes a day for 30 days between May 22 and July 31, recieve a prize. Go here for chart and more details.
Barnes and Noble - Children going into 1st grade up to 6th grade can get a reading chart in the store and keep track of the number of age appropriate books they read this summer. By meeting their level, they can take their tracking sheet in store to pick out a free book (from a list). In addition, there is a theme this year that 3rd-6th graders can participate in more activities. See your store for more details!