Stanford and many other universities have made videos of class lectures available for free via youtube and other outlets (such as iTunes U). Let's pause for a moment and appreciate that. Holy crap! You mean I can learn linear algebra from Gilbert Strang? Why, yes you can! I don't want to make too much of it. I suppose this information has been available since we've had public libraries, but it just seems like there are no excuses anymore.
I combined my love of learning with my love of running and hatred of heat and humidity by watching the 30 video lectures of Brad Osgood's Fourier Transform course while running on the treadmill. I picked the course because someone had sent out a link at work about 6 months ago that I saved and then I was working with our Fourier Transform IR and realized I didn't know as much as I'd like about Fourier transforms.
Here's my brief review: It is un-****ing-believable.
He's a mathematician at heart and he lets you know when he's cheating and introduces much more rigor then you'd expect in an engineering class, but he doesn't let it bog him down. He motivates the lectures with history and lets you in on where the big steps are, usually with a sarcastic, "What could be more obvious?" How many times have you heard a professor dryly recite a derivation that's one of the crown jewels of civilization as if it were obvious?
He also appreciates the applications and uses them as motivation. The use of the diffraction problem to introduce sampling and interpolation is really original.
Beyond that, he's just an excellent communicator. You always know where you are and where you're going. He outlines the steps beforehand, gives guideposts along the way, and summarizes with "Where did we start and where did we finish?" It's really just excellent stuff.