Geeking Along

I've started to play with ipodder and have subscribed to a few things almost at random including the BBC 'In Our Time' trial and Grape Radio. What I want to know is.... what are the 'must listen' mp3 feeds out there? I'm after any and all suggestions - I may not use them all, but it'll be nice to know what others view as essential.

Elsewhere, google news is now customisable.