Powertrip's Journal: Organizing Video amongst multiple formats

With my media collection growing as fast as the latest hard-drives, my organizational structure for all my movies and videos is lacking. I am finding that many of my movie files end up being converted to another format to fit my iPod, down-sample them so I can stream them or use on my laptop, or create a new version for the Apple TV. I seem to have 2 to 3 versions of these files now, and my organizational structure is non-existent at best. How does everyone else cope with all the different video/media formats? Are you keeping multiple copies, or are you 'converting' on the fly when you need to?