A wide variety of academic subjects, presented in the format of short lectures (video).  Simply presented for non academics.

http://academicearth.org/

Well worth an exploration !

Really nice, I´m already refreshing some skills and knowledge. I love these types of sites.  Thanks!

Actually, this would be a nice thread to keep alive.  As we find educational sites, we could add them...a

There´s a number of sites of this kind. In the US many universities decided to avail their lectures and notes to general public. Some of my favorites are The World Lecture Hall and the MIT one. I love those sites too, especially since there are so many things I am interested in and I either don´t want to pay tuition or the classes in local colleges are not available at a convenient time for me. University of Berkeley also has great lectures available on YouTube (I´m at work right now and YouTube is blocked, so I can´t add the link).