Open-textbook

http://en.wikipedia.org/wiki/Open_textbook
http://www.opentextbook.org/
There are several NGO initiatives to give free access to books for more students. Currently the most popular location for legal open textbooks are: WikiBooks, Connexions, OER Commons, MERLOT, and the Community College Open Textbook Project. Although the number of open textbooks are increasing there are several issues regarding compensation and legality that need to be resolve before the open-textbooks become mainstream.