At iTunes you can buy a song for 99 cents.
And while you are there you can download an entire course on theoretical physics by world-renowned Stanford professor Leonard Susskind. For free.
Although it launched just over a year ago, iTunes U now offers more than 50,000 free audio and video tracks – course lectures, language lessons, speeches, etc. – from dozens of universities and colleges, including the likes of Duke, MIT, Stanford, the University of Michigan, the University of Pennsylvania, Vanderbilt, and Yale. There’s also a variety of lectures and videos from prominent non-academic institutions like American Public Media, the Museum of Modern Art, the New York Public Library, the Smithsonian, NPR and PBS. [1. San Jose Mercury News, 7/28/2008]
Any iTunes U course can be downloaded to your home computer with iTunes software (a free download that works on Windows PCs), or you can buy an iPod for $50 and have a portable university where ever you go.