My kids have done this program the past couple years. It's fun and easy and helps keep them reading all summer long.
From the Barnes & Noble Summer Reading Website:
Kids Earn a Free Book!
Here is HowStep 1. Fill out the Summer Reading Triathlon Reading Journal (PDF).
Step 2. Bring the completed Reading Journal to your local B&N store. Find a Store.
Step 3. Choose a FREE BOOK from our selection on the Reading Journal list at the store... Enjoy reading!
Our closest Barnes and Noble is about an hour away, so we usually combine it with some other summer field trip I plan with the kids and hit up the one at the Mall of America.
If I had to guess what books they would pick, I am sure my daughter will pick the American Girl one "Lea Dives In". For my son, I am inclined to say he might pick out the "My Big Fat Zombie Goldfish".