Stanford's digital photography course is online in its entirety — but be aware, it gets technical
If you've ever wanted to garner a more technical knowledge of how photography works, check out this incredible resource from Stanford University. The entirety of the 2011 "CS 178 - Digital Photography" course is available online. Unlike most photography courses, this deals less with how to take a good photo, and more with the scientific and technological basis of how photography works. It's run through the computer science program, which should give you some warning about what you're in for.
There are also a series of applets which delve deep into how various parameters can alter the outcome of your photographs. You can even do the assignments, if you like — though unfortunately you won't get any class credit for completing the course.
This content has been online for a few years, but is still an incredible resource. While most photographers have a decent understanding of the basic, optical side of photography, delving into the computer science side of things is a bit trickier than learning how focal planes work. So if you're interested in that side of the field, this is an incredible resource.