Ben Hammersley wrote a little perl script – Radiopod – a while ago. It uses mplayer and the lame mp3 encoder to create mp3s of RealAudio streams, which are then usable on iPods and other portable mp3 players.
I had a bit of a nightmare getting set up on OS X, though. At first I tried installing mplayer and lame using Fink; this didn’t work, so I switched to Darwin Ports. This was fine for lame, but the DP version of mplayer didn’t play ball with downloaded RealPlayer codecs.
I then googled and stumbled upon this blog entry where the author describes how to set up lame and mplayer on OS X, for use with his own shell script.
Anyway, there it is: install the ffmpegx version of mplayer and all will be well. I can now listen to Gilles Peterson and Hotpot Radio (Mr. Scruff & Treva Whateva) on my iPod. Yay!
An aside: one of the limitations of Radiopod was that the start or end time couldn’t be after midnight. This is a bit of a limitation, as most of the shows I timeshift are late-night ones. I modded the script to take a duration option (in seconds), which the script then uses instead of the duration it calculates from the start and end times anyway. If I pull my finger out, I may submit my patch back to SourceForge.