MIT's open courseware

Excerpts from the OCW site:

a free and open educational resource (OER) for educators, students, and self-learners around the world.

MIT OCW:

• Is a publication of MIT course materials
• Does not require any registration
• Is not a degree-granting or certificate-granting activity
• Does not provide access to MIT faculty
  

http://ocw.mit.edu/index.html

And MIT is part of the OCW consortium which can be found here: http://www.ocwconsortium.org/