This weekend I've been enjoying Pandora Presents: the Musicology Show, an internet radio show (or "Podcast", if you must, but I hate that word) which breaks down music theory concepts into easily understood chunks with plenty of examples. I'm trying to develop a more analytical ear for music (this is partly spurred by Guitar Hero / Rock Band), so a show that explains time signatures, chord progressions, major/minor keys, etc. with audible examples is perfect.
Pandora is best known for their internet music radio service which lets you create a custom radio station of your favorite musicians, and suggests other stuff it thinks you might like. I've been somewhat disappointed with it, because it tends to suggest songs that I already own, so it's not much different from just letting my iTunes play on random. But the algorithms they use to come up with suggestions &emdash; the so-called "Music Genome Project" &emdash; now that's interesting. (Unfortunately it also appears to be mostly secret.)