OK cool. Keep the ideas coming - some good ones so far.
I'm going to try to work on modularising the effects so that colour mode/cycle speed works independently from the movement (I've already done this crudely and you get some neat effects through combinations of animation speed and the speed at which the next colour is fetched from the colour table).
I'll then end up with a library of animation effects which, should make coming up with effect combos a ton easier.
Doing different graphics (apart from the squares) is definitely doable - I did a version with stars already actually just to test it out. Have to figure a way to be able to switch the graphics with minimal screen fuck up though.
Have a full A-Z, 0-9 font now. I didn't realise that my favourite CHR editor (yychr) can work with 1-bit fonts. Makes it a total breeze to add a new font (yourself too!) for the big scroller