This is excellent and a great teaching tool. I tried putting something like this together a while back as a Java applet for one of my classes but couldn't get the color ordering function to work correctly. Did you use HSB?
Yeah indeed, well, hsl with varying hue and set saturation + luminescence - see https://github.com/lorenzo-stoakes/Rainbow-Sort/blob/master/....
I experimented with RGB and it really didn't work, HS(B/L) work a million times better. Took a bit of trial and error!
https://www.dropbox.com/s/0pjmjllmqh1x4ap/Screenshot%202014-...
I'm going to experiment with HSL and see if I can get it to work. Thanks again!