This list will continue to grow over time and will be updated accordingly, but so that I have a place to track them and to share with others who have asked...here we go:
MyMovies
This add-in manages your DVD collection, either offline (i.e. stored in those stupid containers taking up way too much shelf space) or online (i.e. you found a good DVD backup program that works with your favorite DVD, "Babe the Pig"). It has extensive search functionality, allowing you to view the titles in one single sorted list or search by genre, actors, directors, etc... very cool.
AnyDVD
A great backup program, plus they have converters that can convert to Zune, iPod, or your other media players. They seem to release updates on a pretty frequent basis as well.
PowerDVD Ultra
While the OEM of my machine was able to provide an OEM-only version of another Cyberlink product called Play Movie, unfortunately it absolutely blew up on "Transformers". Another $99 later, I can watch "Transformers" (and actually get my surround sound since the Play Movie product only outputs 2 channels for HD-DVD...lame!). It doesn't integrate with Media Center, but it works...that's about all I can ask for these days.