Converting the audio of a DVD into a WAV is a piece of cake, with the right tools and if one is willing to use the command line:

mplayer dvd://1 -vc null -vo null -ao pcm -quiet -mc 0 -ni

This is already pretty neat, but I usually want to convert backup the DVD’s audio into an Ogg Vorbis stream. This is possible without an intermediate wav file:

mkfifo pipe
mplayer dvd://1 -vc null -vo null -ao pcm:file=pipe -quiet -mc 0 -ni &
oggenc -o out.ogg - <pipe
vorbisgain out.ogg
rm pipe

Yet another example of the power of named pipes