DVD Profiler from Invelos Software is one of my favorite programs. It allows you to catalog all of your owned DVDs with user supplied cover scans, features lists, cast and crew, etc. It is very useful for keeping track of a large DVD collection (I have something like 500+ DVDs). You can even track when you loan them out to friends and family, rate them and do searches by actor, director, and other criteria.
It is very helpful when you are out and looking at a DVD and wondering if you already have that one..a quick check of your online profile page will show you all of the DVDs you own.
I recently upgraded to the new version 3.0 for $29.95 and its worth every penny of that small investment for the time it saves me in keeping up with my collection.
You can check out the online feature here by viewing my listing.