iTunes U

[YellowJacket RV9]

I'm not sure how many have discovered this, but for iPad users there are tons of very interesting aviation/engineering video and lecture series for free on iTunes U. UND has a full course on ATC which I am watching right now, very helpful for an IFR student/pilot. Lots of more advanced aerospace/engineering courses and content as well.

[Buggsy2]

There's also a lot of aviation podcasts...my favorites are Aviation Story, The Finer Points, and The Pilots Journey. So many ways to waste time...though, the podcasts are a great background noise while building.