Patrick Rhone recorded an entire audiobook without any additional software (including GarageBand):
Then, it dawned on me that I could use Quicktime. I opened up Quicktime Player and chose “New Audio Recording” from the File menu. I opened the PDF in [P]review, hit record, and started reading. Then, I hit stop when I was done, listened to the recording to make sure I was happy with it, and then saved it as an audio-only file. It couldn’t have been easier.
QuickTime is ridiculously powerful, especially when paired with the now-discontinued Perian. If you have QuickTime 7 Pro (which, by the way, Apple should bundle with OS X), it’s even better: you can isolate audio tracks, video tracks, various other content, and export with myriad of encoding options. It’s not really “built right in” in the sense that Rhone uses it, though. I’m amazed at how much he did solely with QuickTime X.
Rhone mentions Preview in passing here (it’s not the focus of what he was doing), but it’s one of the pieces of software that specifically establishes why I remain with OS X. The range of tools that it offers is astonishing.