What it is? Easier to just copy-paste stuff from their site.
MIT OpenCourseWare (OCW) is a web-based publication of virtually all MIT course content. OCW is open and available to the world and is a permanent MIT activity.
What is MIT OpenCourseWare?
MIT OpenCourseWare is a free publication of MIT course materials that reflects almost all the undergraduate and graduate subjects taught at MIT.
* OCW is not an MIT education.
* OCW does not grant degrees or certificates.
* OCW does not provide access to MIT faculty.
* Materials may not reflect entire content of the course.
So there you have it. I took a peek at Foreign Languages and Cultures to start with, and what little free time I had got thrown out the window. Some of the courses feature videos of the lectures, so we're talking lots of otherwise expensive stuff for free..
I just figured you lot might be interested in it as well, so here ya go:
edit: fixed spelling mistake.