http://www.stationripper.com/
"StationRipperTM allows you to record Internet Radio broadcasts. Users on broadband connections regularly report 3,000-6,000 new songs can be downloaded every 24 hours with the registered version! "
The shareware version only works for 30 days and will only do one station at a time. It spools the music from an IRB to a file, then clips the file, names it, and stores it as an mp3. One song, one mp3.
The registered version will do 6 stations at a time.
I hope to god you've got some free drive space (this will fill it quickly!).
If you want to buy it... it's only $14.99