Massachusetts Institute of Technology: MIT has made virtually all of their course content available online for free. Courses are presented as video lectures. Information about the textbook(s) used at the school is available, but textbooks are generally not required. Some courses suggest projects; some have Online study groups available. ocw.mit.edu
Harvard: Harvard offers a number of video lectures you can watch for free and without registering. http://www.extension.harvard.edu/open-learning-initiative
EdX is a non-profit founded in partnership by Harvard and MIT. Additional partner colleges and universities include Cornell, Berklee College of Music, Boston University, Columbia University, The University of Queensland, Australia, Dartmouth, Caltech, McGill, Georgetown, Kyoto, University of Chicago, Wellesley, and others. Over 150 free courses; requires registering, certificates of achievement are available. https://www.edx.org/
University of California Berkeley: Each semester UC Berkeley records several courses, making them available free to the public. New lectures are posted to the web weekly for the duration of the course. The webcast classes are archived for about a year, then removed from distribution. These are lectures only; there are no assignments, reading lists, or interaction with professors or other students. Courses are also available on YouTube and through iTunes U. http://webcast.berkeley.edu/
Yale: Free and open access to introductory courses. The lectures were recorded in the Yale College classroom and are available in video, audio, and text transcript formats. http://oyc.yale.edu/
University of Pennsylvania: This link will take you to information, including a video, about this program. http://provost.upenn.edu/initiatives/openlearning