I've had pretty good luck with the trial version of DVDxDV. The user interface is horrible (bad enough that I won't pay for the full version, despite its usefulness), but once you fiddle with it a bit, it does extract audio from a DVD quite well.
I've used it a few times to extract audio from some concert DVDs:
Extract audio to one big AIFF file.
Play the DVD in DVD Player and use forward/back buttons to get approximate times of track starts and stops.
Use SoundStudio to split the big AIFF into separate files for each track.