Yesterday, a very nice blogpost appeared over at onlinecollege.org: 100 Incredible Open Lectures for Math Geeks. In this post, they have collected and organized 100 sets of lectures within several fields of mathematics, like Algebra, Calculus, Geometry, etc. Towards the very end of the list, there is even a collection of lectures related to teaching! The lectures are from some of the best universities in the world, like Stanford, MIT, Princeton, Harvard, Berkeley, UCLA, etc. The lecturers are of course also extremely good. For instance, you’ll find a lecture that includes Professor Terrence Tao from UCLA. Professor Tao is arguably one of the best mathematicians of our days, and he has received numerous awards, like the Fields Medal (in 2006). I also recommend the lectures of Professor Gilbert Strang (MIT) in Linear Algebra. Several of the lectures from the list are from Academic Earth, so you might want to check out that site as well.
This is a very useful list, and as it is said in the original post:
You can indulge your love of mathematics in these great lectures and lecture series. Some are meant to review the basics and others will keep you on the cutting edge of what renowned researchers are doing in the field, but all will help you expand your knowledge and spend a few hours enjoying a topic you love.