from MIT, Stanford and Caltech.
Some really interesting stuff.
Udacity
Stanford
Computer Science 101 http://www.cs101-class.org/
Machine Learning (one of the offerings this past fall) http://jan2012.ml-class.org/
Software as a Service http://www.saas-class.org/
Human-Computer Interaction http://www.hci-class.org/
Natural Language Processing http://www.nlp-class.org/
Game Theory http://www.game-theory-class.org/
Probabilistic Graphical Models http://www.pgm-class.org/
Cryptography http://www.crypto-class.org/
Non-computer science courses:
The Lean Launchpad http://www.launchpad-class.org/
Technology Entrepreneurship http://www.venture-class.org/
Information Theory http://www.infotheory-class.org/
Model Thinking http://www.modelthinker-class.org/
Making Green Buildings http://www.greenbuilding-class.org/
Anatomy http://www.anatomy-class.org/