D-Vision is a powerful tool to work with video and audio from DVD's. I have recently been using this to put OGM files on a video ipod, but there other useful tasks that can be done with it.
Including the ability to:

encode DVD movies in Divx, Xvid or h264.
extract sound of a DVD in MP3 or AC3
encode AVI and MPG files in Divx, Xvid or h264
cut AVI files
merge AVI or VOB files
encode audio file in MP3 or AC3
demux OGM files