Here is another ffmpeg recipe. This time extracting the audio portion of a flash, or .flv, video file.
ffmpeg -i example.flv -ab 56 -ar 22050 -b 500 example.wav lame --preset standard example.wav example.mp3
You can also go directly to .mp3 from .flv using ffmpeg with a command like this.
ffmpeg -i example.flv -sameq example.mp3
But using lame seemed to give better results, as far as I could tell.