Extract Audio is a Nautilus script that will allow you to extract the audio from all media files acceptable to ffmpeg. It gives options of output format, channels, and bitrate. It easily does batch extractions where some files need to be treated differently than others.
It is very useful when coupled with the Firefox plugin DownloadHelper (no association) on sites such as youtube and imeem. Use DH to get the .flv file then use Extract Audio to get only the music in MP3 player compatible format.
To use this script, extract the .tar.gz file into /home/USR/.gnome2/nautilus-scripts/
If it doesn't appear in your scripts context menu, you may need to use "sudo chmod a+x '.gnome2/nautilus-scripts/Extract Audio' "