Of course there is econlib and econtalk!

There’s a girl giving lectures on youtube on economists do it with models.

Maybe there’s something useful on David Levine‘s page. He has lecture notes and exercises. He also links to Open Text Book, a site promoting open source textbooks (But there is only an econometrics textbook available…).

McAfee has a introduction to economic analysis online. The revised version is available (for a fee) on Flat World Knowledge (You can read the book online for free).