Check out Academic Earth. http://www.academicearth.org/
I’ve been wishing for this for years. Not everyone with a “Walkman” is listening to music. Some of us listen to lectures. Now it’s even better. Complete course lectures from some of the best schools, Yale, Stanford, MIT, in high quality video. Biology, physics, engineering, law, history, economics, medicine, you name it. And the collection is constantly growing.