Online U-s

The best known online U is iTunes U
At Peer to Peer you can either take or teach a course. No fees involved, and the courses seem to be taught by qualified people.  P2P.  The same is true of the University of the People
The Sloan Consortium is a group of educational and professional organizations dedicated to online learning. A good place to find out about different conferences and symposiums.
The biggest actual university making its course material available to everyone is MIT