These were fun! This would be the first I realized that really awesome stuff can happen when a microcontroller is attached to a LED and the LED is embedded in acrylic.

This "white" is produced not by adding "red", "green" and "blue" but by sequencing these colors extremely fast. Read below for an explanation of the significance of this.
If there has to be something that would be considered the predecessor to  PoiPlay, this picture would be it. One of the sequences in the Two Towers was one where the colors Red, Green and Blue were cycled to produce "white". Funny thing happened when people would glance either toward or away from the towers -- the colors would persist in space and would show the atomic colors.