So you just bought an iPod touch or iPhone and want to stock it with movies from your DVD library. There are countless commercial utilities that promise to rip DVDs, but I recommend trying HandBrake. This open-source (read: free) utility for Windows (download), Mac (download), and Linux converts your DVDs for viewing on iPods, iPhones, Sony PSPs, and other portable media players. It's by no means new, but I just had to share my newfound appreciation for it.
I recently picked up the hilarious Flight of the Conchords on DVD. I also just acquired an iPod touch (quite simply the coolest gizmo I have ever owned). I wasn't about to pay iTunes for a show I already own, so I fired up HandBrake. A few hours later, presto: New Zealand's fourth most popular digi-folk duo appeared on my iPod.
Note that because most commercial DVDs are copy-protected, HandBrake can't work its magic without a decryption utility running in the background. Rumor has it that DVD43, also free (but Windows-only), works really, really well.