saylor.org

A free, open collection of college course material hosted by Saylor Foundation. It is designed to replicate an entire college curriculum with freely available course materials, although they do not offer college credit. (Eventually they will to host all materials on their own site so they can ensure long-term stewardship, but in currently some is available only through links to other sites). Currently the courses consist largely of recorded lectures and readings. There are a few quizzes, but few interactive materials or tutorials.