How about a "liquid" or "plasma" visual? I'm thinking lava lamp like blobs...
I was looking at a book of photographic plates used to record the paths of excited particles. Basically they look like curve rays, as the particle presumedly bounced off of obstacles, creating a fractal like natural curve that's very pleasing to the eye. If this can be modeled somehow that would be very nice indeed.
There is this cool effect you see sometimes on TV, when a video camera operating at a different frequency is filming a video monitor, you see a bright scan line moving slowly vertically across the screen. That looks damn cool i must say....
Finally, I would put forward an enhancement request that when I power down the empeg, the screen should flash completely bright white for a split second, and then it would contract horizontally and vertically until there is a small dot remaining in the center of the screen that fades away. Kind of a nod to the old CRT days.
:-)
Calvin