This is a curated list of free courses from reputable universities like MIT, Stanford, and Princeton that satisfy the same requirements as an undergraduate Computer Science degree, minus general education.
Textbooks in the Open Textbook Library are considered open because they are free to use and distribute, and are licensed to be freely adapted or changed with proper attribution. The criteria for including new textbooks in the Open Textbook Library are:
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.