Apple's iTunes U has reached 600 million download since it launched in 2007.
The education-oriented "store," whose slogan is "Learn anything, anywhere, anytime," has over 1,000 universities active, including Harvard, Cambridge, and Oxford. Stanford University alone accounts for more than 30 million downloads.
30% of iTunes U traffic now comes from iOS devices. The service is availble in 123 countries, resulting in roughly half being outside of North America.