For years America's largest academic institutions have been contributing to a social project called Open Courseware. The idea is simple: provide anyone who wants to learn with free classes including lectures, materials, etc. from hundreds if not thousands of higher learning institutions. The idea is that by lowering the barrier to high quality education more people would want to learn.
I've browsed the course selection over the years and currently I find myself watching a lecture series from Yale on an Introduction to the New Testament History. I found it through Open Yale courses here and then downloaded the video files through iTunes University for free.
Despite Open Courseware's growth of content over the years I don't think it has caught on nearly as well as many would have liked. Now comes a new entrant into free, high quality education online called Khan Academy.
The founder, Salman Khan, has been creating videos on a wide range of subjects including algebra, history, investing, banking, etc. in simple and easy to understand format that can break down even the most complex topics into several 10 minute YouTube videos. He's also been doing this full time as a not-for-profit institution to help people learn more. (You can find a number of video's about him and his background online).
The Khan Academy has been generating a lot of buzz including getting funding from a number of silicon valley big wigs. It appears his types of classes has taken off far more than those offered by Open Courseware and with good reason - they deal with far simpler subjects.
I just finished a video lecture on the Paulson Bailout. Check out the Khan Academy at http://www.khanacademy.org/.
For More Information on Open Courseware:
MIT's Open Courseware
The Open Courseware Consortium