I have no idea what they’re saying most of the time, but I have become hooked on the live air traffic control streams offered by LiveATC.net. One may listen for free through the website (which also comes in a mobile flavor), or through a $2.99 iPhone app.
As of this writing, there are 498 available feeds, and more are added on a consistent basis. As I said, I don’t understand much of it, but it makes for a relaxing background drone as controllers chant their arcane codes and instructions. It’s worth a listen for anyone who is interested in aviation, or who enjoys eavesdropping on inscrutable radio broadcasts.
Perhaps listening to it will prepare me for when I summon the courage to start using VATSIM, though I doubt if that will ever happen. As much as I love flying virtual planes around, I’m hesitant to waste the time of other live humans; I still tend to make dangerously fast approaches when it’s time to land, and even taxiing can be a gamble.