Columbia University is reaching out to the world and attempting to bring science to the masses, promising to make it visual, interactive, and exciting.
From Science to Art to Technology, edX offers classes from the best professors and universities.
A fantastic culture blog that also has a collection of over 800 free courses. This link directs straight to a well organized list of their courses.
This is a fantastic aggregator that is easy to use and has classes from over 100 partners.
From astrophysics to cognitive psychology, this is a great list of free classes available from top universities in a variety of scientific fields.
Each course includes a full set of class lectures produced in high-quality video accompanied by such other course materials as syllabi, suggested readings, exams, and problem sets. The lectures are available as downloadable videos, and an audio-only format.