Aside from using AHP for recording Coast To Coast AM streams for later iPod listening, I also use it to capture and tweak (but not record) iChat AV audio output - adding an equalizer module lets me boost the high end of the iChat audio to compensate for people who are using the "pinhole" microphone on their iMacs or whatever. The ability to modify the captured app's audio is something I didn't really think much about when I registered this, but I find I use it quite a bit now. Wiretap looks like a nice bare-bones audio hijacker, and Ambrosia is a great developer, and that might be enough for casual users. AHPro though has these advantages for people who want more flexibility:

• You can set up a list of timed recordings to match assorted streaming broadcasts (or just to record a few things in a row while you sleep).
• You can modify a specific app's audio output with various effects like an equalizer and stuff.
• Since you're only hijacking a certain app's audio, other apps can make all the noise they want, and it won't effect the recorded stream.

I could write a script to force Wiretap or something to do timed recordings (well, I assume I could), but my time is worth more than the $30 it took to register this...