TL;DRAdd colors such as Orange or Purple to the signal network and to the colors implemented by lamps.
What ?Currently there are 9 color signals: red pink blue cyan green yellow white grey black. However, the last two are not recognized at all by lamps. Furthermore, white has a significantly different behavior than the other 6 colors. White casts a large diffuse light (standard lamp behavior) and the other six colors have a much smaller, much more intense circle of light.
Effectively this means that color coding things visually with lights only has 6 colors to use. More colors would allow for more options. It would also allow for more color depth if you go crazy and start converting images to giant arrays of lamps.
A baseline would be to implement white and grey to behave similarly to the other 6 colors. Black would also be neat, although it's not at all clear how a lamp would project a small circle of blackness.
A further extension would be to add signals such as Orange (255, 128, 0) and Purple (128, 0, 255). Even more options could be made available with dimmer versions of the existing colors, such as signal-dark-green in addition to signal-green.
The ultimate solution would be adding another mode to the lamps such that the color displayed is the actual RGB color based off the Red, Green, and Blue signals coming in.