Instead of having students do a traditional book report, have them add to a classroom book where students can review and recommend (or discourage) other students from reading a book.
I had my students choose a book to read (giving some page length requirements) and when they finished the book, they had to fill out and turn in this book recommendation worksheet. Within two years, I had quite a collection of book recommendations written by students for students. I simply slid the completed worksheets into sheet protectors and put them in a three-ring binder. My current students still browse this book to find book suggestions.