Porn on your iPod
Mark Pilgrim has put together a quick how to called 'HOWTO Put Porn on your iPod.' His method works equally well with porn, or with home movies, or home made porn for that matter. The tutorial relies heavily on ffmpegX, which is a shareware application that can convert video from one codec (let's say .avi) to another (in this case MP4 H.264).
Mark doesn't mention this, but I am pretty sure if you want the best results you should have the latest version of Quicktime on your Mac, though it doesn't have to be a Pro version.
Happy converting!