Textbook Revolution is intended to be a primary online source for finding free educational texts. This is a student-run, volunteer-operated website started in response to the textbook industry’s constant drive to maximize profits instead of educational value.
TBR’s mission is to drive the adoption of free textbooks by teachers and professors. We want to get these books into classrooms. Our approach is to bring all of the free textbooks we can find together in one place, review them, and let the best rise to the top and find their way into the hands of students in classrooms around the world.
Found out more from the (somewhat dated) site at textbookrevolution.org.
 About the new site
The new site will be a community driven, Wiki-based web site that is simple to use. Visitors can upload reviews or new books through simple forms, link to existing books in different formats, or help us redesign the site by creating new templates. Helping is as easy as tagging a book with an appropriate category, or as complicated as helping us getting two disparate wiki sites to share their metadata.