Online courses are now available from many legitimate and well known universitites. Stanford University, one of the top US universities, has many online computer courses. Here's a list of some courses available. More courses may be added later.
CS 101: http://www.cs101-class.org/
Design and Analysis of Algorithms I: http://www.algo-class.org/
Computer Security: http://www.security-class.org/
Software As A Service: http://www.saas-class.org/
Machine Learning: http://jan2012.ml-class.org/
Human-Computer Interactions: http://www.hci-class.org/
Game Theory: http://www.game-theory-class.org/
Anyone can sign-up at the website of the corresponding class.
You can watch the lectures at your leisure.
These courses are available only for learning the subject. You cannot get University credit or certification.