Thanks for the comments folks, I've nearly tidied the code up so I'll post that in a bit.
I considered adding music, and even popped the code in and threw a tune at it. However, it didn't really fit as I kept changing what the demo did so the music would never be more than a simple backing track. You may as well simply pop a tune on your PC and play that whilst watching the thing

I like it, but there're more envelopes to be pushed 
Jim
Hehe, I know. This is hardly groundbreaking or even nudging envelopes. It started as a little concept but I kept adding things to it (without any coordination or planning) simply because I could.
As a result, rather than trying to wrap a full demo around it, I figured I'd step back, take what I'd learned and plan (scary concept) something bigger.
I intend to use that proportional font quite heavily for all sorts of things, including a game project that I have planned (there's that scary word again).
I had fun (?!?) coding the plasma, drawing from a source in C I found on the net. I had to change some things to make the gradient smooth (the original code had definite banding), which confused me for a while and then I threw it down to a single colour.
There is a commented line in my source that changes the plasma colour but it didn't look right for that use as the background then started to attract more attention than the text. It also messed up the anti-aliasing on the font as I'm cheating rather than using alpha mixing.