Flickr: EditorB
Last week, Bill Gates made headlines with his quote about how the web will be better than any single university in the next five years. I'm not sure I'd go that far, but in the same spirit of furthering the cause of online education, here's an article from Lifehacker listing the best free sources.
Some highlights: Wikiversity, Textbook Revolution, online textbooks from universities, iTunes U, Academic Earth, and the Khan Academy.
Definitely worth looking into.