WARNING! This website is no longer actively maintained. It is an archive of 2 years work by Doug Belshaw who now blogs at dougbelshaw.com...
In 1999 the Massachusetts Institute of Technology looked into how to provide high-quality distance learning/e-learning courses. They decided that, consistent with their mission (to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the 21st century) they should make their courses freely available to all via the Internet. This has matured and developed over the last six years to become an impressive resource for teachers and students alike.
There are a great number of courses available, from Aeronautics to Writing Studies, some of which have audio and video to accompany the readings. It’s a great way of extending your knowledge in a given area - for example my two main subjects (History and Philosophy) are fairly well represented and I used the site to start my more in-depth research of the Russian Revolution last summer.
Other universities and educational institutions have jumped on the bandwagon, including Utah State University, Johns Hopkins University, and Carnegie Mellon Open Learning Initiative. A handy search function of all OCW sites is available at opencontent.org/ocwfinder! 
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I’d certainly agree that it was a revolutionary move and one for the ‘greater good’. What is a pity is that most of the open courseware is not much more than a reading list together with a few resources. This is really not much more than many University lecturers do anyway now.
What would be great is if the lectures were recorded and shared online. Not sure many lecturers would agree to this though - after all, it would potentially make them redundant.
I agree, Andrew, but if you look at the more recent courses (i.e. 2004/2005) you’ll see that a few of them do indeed have Realplayer-streamed lectures. I viewed the one on the Philosophy of Film, for example, which was excellent!