First, check out my annotated directories: Best free courses & lectures, and Guide to iTunesU.
For further browsing, look at the great collections of courses at Stanford, UC Berkeley, MIT, UCLA, and UCSD.
And the web has quite a few directories of courses listed by subject.
These two directories include all subject areas.
These directories focus on science and math with some social science.
Filed under: Courses, Getting started
[...] on global warming issues. – apple.com/itunes One blogger made a guide to iTunesU: diyscholar.wordpress.com/2007/12/18/how-to-begin ~ Social Innovation Conversations – Offering lectures, debates and conference recordings on social [...]