Open Courseware is the term for study material, courses and lecturers created by top universities and shared for free on the Internet. Some of the most popular courses are offered by Academic Earth. Here is an example of just a few of their free courses:
Introduction to Psychology - Yale, Political Science - Princeton, Entrepreneurship - Stanford University, and General Chemistry- Berkeley.
Here are the links to additional open courseware web classes offered at these top universities: MIT, Stanford, Utah State, University of California at Berkeley, Notre Dame, Yale, Tufts, and the University of Massachusetts, Boston.
If you are already a college student, you might download the free courses that correspond with the classes you are taking to use as a study guide and preview future classes. Deciding on a major? Take a look at the classes you will need to take.