Ha, this is awesome. I tried to carve out some free time at night to work on something similar for our game engine, and never got too far with it. I'm definitely going to try integrating this and see what it's like.

I've used some tools like Telemetry before:

http://www.radgametools.com/telemetry.htm

And while it was pretty powerful, I found the process of adding custom data visualizers pretty handicapped by their native interface requirements.

With the current state of your code, how hard would it be for someone to add plugin based functionality to implement custom data messages and visualizers?