Free Knowledge/Education/Reference Material
Open Courseware Consortium is a group of universities offering online courses for free. Their course catalog is still in beta, but it's an easy way to view jillions of courses that are available for free.
MIT Open Courseware 2,100 courses available for free as of 5/15/2012
Coursera: Offering free education for everyone/courses from the top universities for free
Wikibooks: The Open-Content Textbooks Collection that Anyone can Edit
(computing, engineering, humanities, languages, mathematics, miscellaneous, science, and social sciences; as of 5/4/12, 2,444 books with 41,116 pages)