HandBrake is a GPL'd multi-platform, multithreaded DVD to MPEG-4 
ripper and
converter. HandBrake was originally available on the BeOS, but now has 
been
ported over to MacOS X, GNU/Linux and FreeBSD.

Features:
 * Can encode directly from DVDs (even encrypted ones) or from 
VIDEO_TS folders
 * Supports AC3, LPCM and MPEG audio tracks
 * Outputs MP4, AVI or OGM files
 * Outputs AAC, MP3 or Vorbis audio
 * Supports 2-pass encoding
 * Supports encoding of two audio tracks
 * Includes a bitrate calculator
 * Supports picture deinterlacing, cropping and scaling

Known limitations:
 * Does not handle DTS audio tracks
 * Does not handle single VOB files or any other file format

WWW: http://handbrake.m0k.org/