There are lots of great repurposing projects you can make out of old books.
Making a clock out a book is one of my favorites (plus it's very easy to do)!
Thrift stores are great places to find old books.
Reader's Digest books are both colorful (I love their covers) and easy to find. Plus they aren't considered "real" books, so no one is going to care if you use one for a craft project.