I use
Invelos' DVD Profiler for organizing my collection, and it supports DVD, Blu-ray, and I believe HD-DVD. You can download a free version to see if it's something you want to purchase.
The program allows you to upload your collection database to their servers, which you could then link to in your signature. I'm sure there are free options out there, but I found the $30 for the full version more than worth it.
edit: Here's an example of what the online collection link looks like, using my own:
Milambian's DVD Profiler collection