Here is a great, short(ish) video from Ted.com describing how Stanford University offered an online course in Artificial Intelligence to over 160,000 students, in 9 countries.  The speaker is Peter Norvig (one of the two instructors) and some of his insights regarding student motivation, the power (necessity for) of collaboration and accountability are excellent.

One of their students commented at the end, “This felt like sitting in a bar, with a really smart friend, explaining something you haven’t grasped yet, but you know you are about to.”

Highly recommended:http://www.ted.com/talks/view/lang/en//id/1487