Visit iTunes U. (opens iTunes) This new feature of iTunes provides free lectures from many great universities. A tremendous resource, and hopefully it will expand.

Here's a great article by Michael Erard in Reason Magazine . It explains a little about how I produced this site, and about online peer production

Michael Erard recently wrote a great book: UM

An excellent podcast and blog on the Constitution:
The United States Constitution by Ira Krakow

A remarkable intimate view of the United States Supreme Court: Oyez.net

Sources of online audio books:
Librivox
Project Gutenburg
ibiblio.org
loudlit.org