Free Open Content from the University of Oxford – http://podcasts.ox.ac.uk/
” This free site features public lectures, teaching material, interviews with leading academics, information about applying to the University, and much more.
All the material is arranged within a series of related talks or lectures and may be in audio, video or document format. A full list of all series is available.”
Kan Academy – http://www.khanacademy.org/
“With over 3,100 videos on everything from arithmetic to physics, finance, and history and hundreds of skills to practice, we’re on a mission to help you learn what you want, when you want, at your own pace.”
“We offer a wide range of courses from our partner institutions, spanning the humanities to engineering. Find a course that interests you and join today to learn alongside our global community!”
Note: the sites are arranged in no particular order.