MIT Open Courseware (OCW)
The Massachusetts Institute of Technology offers free public online access to many of their course materials. The OCW website offers free video lectures, lecture notes, quizzes, examples and assignments. Although this is not a replacement for a true M.I.T. education, it can be a great way to expand your mind and learn about something that interests you. Open Courseware allows people to progress through the course material at their own pace, which can be much less stressful than taking a true college course. The only thing missing from the experience is the in-class discussions; and of course the college degree.
Stanford Engineering Everywhere
Stanford University also offers free online classes through their "Engineering Everywhere" program. This program is a little more structured than the Open Courseware offering from M.I.T. With the Stanford classes, students are actually assigned homework problems and quizzes. Although students cannot directly ask the instructor questions, they can communicate with one-another for help on assignments. After taking the class, students will get a "certificate of completion." Sadly this does not translate into Stanford course credit. Most courses are computer-science or engineering related. Some very interesting topics have been offered in the past including "Machine Learning", "IPhone Application Programming", and "Introduction to Robotics." If you are at all into engineering or technology then these courses will be right up your alley.
Many universities are offering course content in the form of podcasts. Just go to the "iTunes U" section on iTunes and you will see free and paid content from places like UC Berkeley, Duke, and Yale. These courses will mostly be self-study and sometimes might not even have the notes/materials to go with them. However, if you have a long commute or other opportunity to listen to your iPod for a while, these podcasts could be a great option.
Clever Google Searches
Sometimes you can find course material by simply doing a Google search. For example, I googled "cs102" and came up with the page for a "micro-computer applications" class. Some of these course websites might be password protected, but many are not. While most are probably not intended for use by the public, I suppose it is the professor's fault for not securing their material. Just beware of any disclaimers because intellectual property theft can be a serious offense. While viewing the material might be ok, copying and distributing probably isn't.