I recommend some useful tools here:

DVD Ripper .
It can rip DVD to AVI, MP4, MPEG, WMV, 3GP, HD video, MP3, WMA etc, put DVD on iPod, iPhone, PSP, Apple TV, Zune, BlackBerry etc and extract audio from DVD to MP3, WMA, AAC, M4A and other audio formats.
Tod Mod Converter .
It can convert digital camera created Mod Tod video to other common formats for all the portable players.
iPhone Ringtone Maker .
It can convert any video/audio to iPhone M4R Ringtone, convert any time length of the video/audio, and put the converted Ringtone on iPhone directly without iTunes