Ethics Bites, the Open University sister series of the Philosophy Bites podcast, is now available on iTunesU together with transcripts. It includes interviews with Michael Sandel, Richard Posner, Janet Radcliffe Richards, Tim Scanlon, Miranda Fricker, Peter Singer, Mary Warnock, and others. Four of these interviews have already appeared on Philosophy Bites, but a further nine are currently available from the Open University section of iTunesU.
iTunesU has an amazing range of free educational audio and audiovisual podcasts. Perfect for the autodidact. The Open University has its own section there as do many of the major US universities and a few other UK ones (including Oxford University).