HandBrake is awesome. I just downloaded it last week and I've already put a couple of movies on my iPhone. It's great because HandBrake can output to a variety of different formats.
Videora Converter for iPod/iPhone works very well and its free.
DVDFab is useful for getting the main movie off the DVD. Its basic functions are free but you can get more out of it if you pay. Basic free function will suit most people.
However, there are loads of options out there. Have a look at www.videohelp.com for suggestions, how-to's and software.