I found another great resource for audio immersion. TBS Radio 954 has a site chock full of downloadable podcasts. They are mostly talk shows, which is perfect. They feature very clear speech as well, so they could be used for sentence mining.
The podcasts are in mp3 format, which means you can load them onto a digital device and carry them with you. There's dozens of hours of content up there that I've grabbed so far, and I haven't even gotten through half the site yet!
It also seems to be somewhat regularly updated, so you can find a few per week on average.