Ans: I polled a couple of colleagues for help with this question and here's what I found out... One of my friends says that TotalRecorder will capture anything that plays to your speakers in Windows. There's also a utility floating around call ASFRecorder that will grab Microsoft audio streams straight off the net (violating the stream-only rule, I think). I think it violates (and predates) the DMCA, so it may be hard to find. (Hint: I've got it around here somewhere.) Comes with source code.
I don't know about a util for RealAudio, though. TotalRecorder works for it, but it has to go through another level of compression. Some of my friends also says that for the Mac, there's a freeware program called StreamRipperX that's worth checking out. Ambrosia also released a nice utility called Wire Tap, which records any audio going out of your Mac. Ritu shares that she's been using the Polderbit Sound Recirder -- It's a Windows program that can record anything that comes out of your speakers. Their web site doesn't really make this clear (maybe because it's translated from the Dutch), but it works fine and you get a 15-day free trial. Once you've captured the stream, the program also makes it easy to split the recording into tracks for recording as an audio CD. I usually use Windows Media Player to burn the CD.