I will be very interested to see what you like out there. Good thread.
I haven't done much yet with podcasts, but along those lines, I REALLY like a cycling CD I bought and loaded onto my iPod. It is the Zooming CD from Ian Jackson. I ordered the set, which also has audio for both walking and running programs. I use the Zooming workout the most (it is specifically for cycling).
http://www.breathplay.com/