PublicRadioFan.com is a cool discovery. It tells you what's playing, right now, on a hundred or more public radio stations, along with what format they're using and other helpful information. Way too few use MP3 (the only popular format that doesn't require its owner's proprietary player), but among them are a still-impressive list: WFUV, KKJZ, WEMU, KRVS, WUNC, KCRW, KPUB, WNYC-AM and FM, KUOW, KUSC (to which I'm listening right now), KXPR, KRWG and NRK. The majority of stations and networks (CBC, BBC and NPR itself) require a Real or a Windows Media player.
Even among the MP3 streamers, the situation is far from perfect. For example, neither of WNYC's MP3 streams is working right now.
And too many sources, such as the BBC and WBGO, use a browser with a RealAudio plugin as the required receiver — a pretty clunky approach.
I think the BBC also uses windows audio codecs. I'll add this to my news page.