Having looked at the podcast directories listed , I went further afield and found loads elsewhere. Added to my bloglines account now is a feed for a BBC 4 programme's podcast - Tracing Your Roots - which looks fascinating.
The advantages of podcasts are many - you can choose from a whole raft of programmes, listen when it suits you, even when you're on the move, and setting up a feed of your favourites to a bloglines account means it's right there when you want it. There really does seem to be something on every subject area.
They have huge potential for teaching and learning purposes - we've had a small taste of their capabilities in that direction with those we've encountered on this Web 2.0 journey.