iTunes U is a section of the iTunes store that houses educational audio and video files for free use by anyone.
iTunes U is a part of the iTunes Store featuring free lectures, language lessons, audiobooks, and more, that you can enjoy on your iPod, iPhone, Mac or PC. Explore over 75,000 educational audio and video files from top universities, museums and public media organizations from around the world. With iTunes U, there’s no end to what or where you can learn.
Check it out in the iTunes Store. I have found many lectures from universities all for free. Take advantage of this.