MIT Open Courseware: take MIT complete courses for free!

MIT's Open Courseware website offers over 1800 complete MIT courses for free to the public. Most courses have lecture notes, exams, etc., and there are a number that have a substantial amount of audio, video, and multimedia content as well.

From the Site:

"MIT OpenCourseWare is an idea - and an ideal - developed by the MIT faculty who share the Institute's mission to advance knowledge and educate students in science, technology, and other areas of scholarship to best serve the world. In 1999, the Faculty considered how to use the Internet in pursuit of this goal, and in 2000 proposed OCW. MIT published the first proof-of-concept site in 2002, containing 50 courses. By November 2007, MIT completed the initial publication of virtually the entire curriculum, over 1,800 courses in 33 academic disciplines. Going forward, the OCW team is updating existing courses and adding new content and services to the site."