Textbook Revolution
http://textbookrevolution.org/

Textbook Revolution is a student-run site dedicated to increasing the use of free educational materials by teachers and professors. We want to get these materials into classrooms. On this site you’ll find links and reviews of textbooks and select educational resources. Some of the books are PDF files, others are viewable online as e-books, or some are simply web sites containing course or multimedia content. This will be added to Student Research Resources Subject Tracer™ .