The Teaching Company – http://www.teach12.com/teach12.asp
The Teaching Company, based in the United States, brings learning right into your home via DVD, CD, and many other media formats, and has been doing so since 1990.
Though their courses are not degree-earning, they are taught by some of the top college and university professors in the US, and cover a wide selection of topics. Most of the courses are college level, however, many cover topics normally taught in high school, such as basic math skills, early world history, and even study skills. Courses at the college level cover literature, business, social and physical sciences, many disciplines within the humanities, and much more.
The materials can be quite pricey, but appear thorough, and the selection of formats makes choosing the most convenient method for you simple.
WikiBooks – http://en.wikibooks.org/wiki/Main_Page
WikiBooks is working to develop “free, open content textbooks, manuals and other texts.” With approximately 250 textbooks in development, they currently cover such diverse topics as US history, paleoanthropology, linguistics, cryptography, lucid dreaming, swing dancing, and much more.
What makes this site special, is that every page is available for edit by anyone who wants to edit it – that means you, me, the guy across the street – anyone. If you spot an error or omission, you’re free to hit the “edit” button and fix things up. Along with that freedom, goes the freedom to create WikiBooks of your own. If you’re versed in a particular area, you can create a section for it. If it already exists, perhaps you could add your information to the existing pages. And you don’t have to do any of it in English, either. You can read existing books, or add your book, in whatever language suits your fancy.