Don't get me started ....
If you like audiobooks, you might want to check out
Podiobooks. Same idea, but you can get chapters released weekly, so it's almost like a serialized book. The only real drawback is when an author doesn't get the next chapter done right away, and you're left with a cliffhanger for weeks (P.G. Holyfield, I'm looking at you).
There are plenty of music podcasts out there, depending on what kind of music you like. You won't hear mainstream artists, but you'll hear bands you won't get to hear anywhere else (for now -- I know of several bands who were big on podcasts who have been signed to label deals; DecemberRadio and Fireflight are both bands that I had permission to play on my show at one time). I'm not going to pimp my own show right now, because I'm on a kind of involuntary hiatus as I try to carve some quiet time out of the evenings to actually produce a show; if you're really curious, there's a button in my sig that should take you there. Without knowing what kind of music you like, I don't really have any recommendations here.
For tech podcasts, you can't go wrong with anything at
http://twit.tv. And if you really want to boost your vocabulary, there's always
Podictionary: The Podcast for Word Lovers. It's short (about five minutes a day), but you learn some interesting things about words.
The Onion does audio and video podcasts. NPR has a huge selection of podcasts, though not all of those are complete shows. One of my favorites it
The Amateur Traveler, if you're at all interested in travel.
The iTunes podcast directory is probably the most complete, though you can also check out
Podcast Alley or
Podcast Pickle are decent directories.