A search engine which indexes where you can purchase over 150 million rare, out of print, new, used, and import-only books online.
A grassroots peer-based education project based around online learning and remote collaboration between small groups of students. They just started up so things are a little thin at the moment. This is an interesting experiment to keep your eye on. Creative Commons.
Rice University is releasing under a Creative Commons license college level textbooks written by professional textbook writers. The texts have passed through a peer review process as well for vetting and fact checking.
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