My current list (the descriptions are copied from the comments field in MC):
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Documentary Archive - Landmark radio programmes from the BBC World Service archive
http://downloads.bbc.co.uk/rmhttp/downloadtrial/worldservice/documentaryarchive/rss.xml---
MotoGPod - A podcast for MotoGP and motorcycle road racing. MotoGPod's primary focus is, as the name implies, MotoGP, but we'll have occasional sidetrips into the world of AMA Superbike, AMA Supersport, AMA Superstock and FIM SBK World Superbike as well. Find out what's going on in the sport that is the pinnacle of motorsport, motorcycle road racing! New episodes every week and a race wrapup after each race!
http://feeds.feedburner.com/motogpod---
In Our Time - In Our Time, BBC Radio 4. The big ideas which form the intellectual agenda of our age are illuminated by some of the best minds. Melvyn Bragg and three guests investigate the history of ideas and debate their application in modern life.
http://www.bbc.co.uk/radio4/history/inourtime/mp3/podcast.xml---
Go Digital - Find out how the digital revolution is changing our lives. Presenter Gareth Mitchell brings you the latest gadgets, novel uses of technology in the far flung corners of the world and analysis of the hi-tech issues that affect you.
http://downloads.bbc.co.uk/rmhttp/downloadtrial/worldservice/godigital/rss.xml---
From Our Own Correspondent - Insight, colour, wit and analysis as the BBC's foreign correspondents take a closer look at the stories in their regions.
http://downloads.bbc.co.uk/rmhttp/downloadtrial/radio4/fromourowncorrespondent/rss.xml---
Digital Photography Tips From The Top Floor - Short and sweet - with non-techy tips that you can put to use immediately. Covers everything from image composition to post processing. No matter if you use a digital point-and-shoot or an expensive digital SLR. With a good sense of humour, Chris Marquardt manages to convey tips for the beginner as well as the professional photographer
http://feeds.feedburner.com/tftf---
All the above seem to work just fine in MC. Thanks to everybody involved for implementing podcasting in MC. Just what I've been waiting for.
Alan