First, Bookopolis has two different ways to get a free book. One is by printing out their READ-O reading bingo card and filling out for a winning five-in-a-row, and then taking emailing a copy or a picture. Another is by logging reading minutes. What's great about Bookopolis is that it's free, and there are lots of great book suggestions and kid reviews, and you can write your own as well. Please be aware that there are external links to Amazon and the like for purchasing books.
Another place to get a free book is from Barnes and Noble. Print out your Summer Reading Journal in English or in Spanish. Read eight books, record the titles and tell your favorite parts, and turn it in for your choice of a selection of books. If I were the right age, I might choose Plants vs. Zombies: How to Save Your Brains or How to Train a Triceratops or John Grisham's Theodore Boone: Kid Lawyer. And there would still be books I'd wish I could choose!
The final suggestion for a fabulous free book (and more than one, maybe!) is our own Fresno County Public Library. Sign up for the Summer Reading Challenge (Reading By Design). The link has detailed information about the challenge for kids and teens, and the prizes the public library will give away. Just for signing up, you'll get to choose a free book provided by Fresno's own Reading Heart. Finish the challenge and get another book (while supplies last). Turn in your challenge log for a chance to win other prizes too.
The Fresno County Library also has a fun thing called Win it Wednesdays - every Wednesday they give away a book! Just scroll down through the blog to find the newest possibility. While you're there, see what other exciting events are going on through the sidebar links.