pdurbin has done a great job and a while ago he also setup a github repos to gather all interesting related links. Here is the page:
http://wonderstudy.github.ioAmong several, we can notice a few courses but not that many, which can be started at any time during the year, without even suscribing, although suscribing is also possible.
Some of them are:
cs50
Introduction to the intellectual enterprises of computer science and the art of programming. This course teaches students how to think algorithmically and solve problems efficiently. (...)
cs164
Introduction to principles of software engineering for mobile devices and best practices, including code reviews, source control, and unit tests. Topics include Ajax, encapsulation, event handling (...)
E1 Understanding computers and the internet
This course is all about understanding: understanding what's going on inside your computer when you flip on the switch, why tech support has you constantly rebooting your computer, how everything you do on the Internet can be watched by others, and how your computer can become infected with a worm just by turning it on. In this course we demystify computers and the Internet, along with their jargon, so that students understand not only what they can do with each but also how it all works and why.(...)
E7 Exposing digital photo
Photography has exploded in recent years as digital cameras have become affordable and easier to use. There are many courses that teach students the artistic aspect of "how to become a better photographer" or "how to improve your eye," but this is not one of them. Instead, students—from one-time users to professionals—become better photographers through an understanding of the technical aspects and terms of a digital camera. (...)
and also E-75, E-76, E-259.
Up to you to continue the list…