[petercooper]

Just sticking to the BBC because it's what I know best, In Our Time is another great radio show (and podcast) - http://www.bbc.co.uk/radio4/features/in-our-time/

It's essentially a 40 minute discussion between the host and 3 leading academics related to a particular scientific, historical or cultural topic. A recent one was Pseudorandom and Random Numbers, for example (also featuring du Sautoy): http://www.bbc.co.uk/programmes/b00x9xjb .. others like Imaginary Numbers, Logic, Logical Positivism, and The Physics of Time were also illuminating.

I'm not sure how much of the BBC's stuff people outside of the UK can listen to, but there are torrents of the back catalog floating about and I don't believe they're being commercially sold anyway. They just go out on the radio each week.

[dazzawazza]

+1 for In Our Time: The host Melvyn Bragg is a great radio host. He is from a literary background and REALLY struggles with any maths topics but he throws himself in and his struggles makes the listener feel at ease. This show draws real experts to the studio as well so you get really interesting discussion.

Another lighter but still interesting podcast is The Infinite Monkey Cage with Brian Cox and Robin Ince [1]. It's part comedy and part science, thought provoking and a little lighter on the brain.

[1] http://www.bbc.co.uk/podcasts/series/timc

[kjhghj]

All of the radio output is freely available world wide - either for 7days after broadcast in their iPlayer app or for some programs - like 'in our time' - the entire archive is available as MP3s