Christian Kienle has introduced Audio Extractor 1.0 (http://audio-extractor.com/), his new application for Mac OS X 10.6 or higher. For a limited time, it’s available for US$9.99 at the Mac App Store in the Video category.
To use you drop your video files on Audio Extractor. When an extraction is finished you can open it, show it in the Finder, use drag and drop, save the audio file explicitly, and send it to iTunes.
Audio Extractor uses QuickTime technology. For every extraction you start, the app starts a background process that does the real work. It works with a 32-bit or 64-bit processor.