Udacity is one of the many free college-type course sites that have appeared this year, and I've done one of the courses all the way through (and then real life caught up with me).
As you can see from their page, the current courses are heavily computer-science-oriented.
The course I did all the way through was Introduction to Computer Science (but it's really an intro to programming, specifically, Python... and Python is really easy as languages go). There used to be a somewhat ambitious timeline, but now you can do these courses at your own pace, and get a certificate at the end:
They have a python interpreter you can run through the browser for the classes that require it. If you're not interested in the computer programming aspects, I do recommend the Stats course, which I started but did not finish (as I've taught that class in the past... I was just checking out what was being taught... but hey, maybe I'll finish it one day).
There's a lot of little quizzes interspersed with the lectures (almost all of which are under 5 minutes per clip), and often they ask questions before they give you the answer... an excellent way to learn if you really try to think about the question and answer as best you can, and then check the result and explanation.
Unlike regular college classes, you can keep redoing assignments until you get it correct -- they are interested in getting people to learn the material, not giving rank order grades.
If you're wondering about their business model, one thing they've done is partner with Pearson, which does standardized testing. For those of us who have had to take professional exams, I would assume the experience is similar - you learn the material however, and then you have a third party test and certify that yes, you do know the stuff.
But this sort of certification is not the only thing they're looking at -- they are also starting to amass student resumes, and they can become intermediaries for Silicon Valley recruiting, or find people to help their next startup themselves.
But it's also fine for people who learn as a hobby, like I do.