Find AudioHijack Pro to be a really good piece of shareware. Use it for timed recording of internet radio streams, peeling audio samples off DVD's and many other kind of tasks. Truly the screen capture app for audio. Seconded!
I've had audiohijack for a while and love that I can easily switch my meters to compare my mixes against stuff playing back out of itunes, and can pop in the vst's for easy comparison of L2 limiting. Don't like that it won't record real audio files- just mp3's, so I still have to go to a full app to print. Maybe I'll try to get AH to meter the output of Wiretap. Keep you posted.