We programmed our Christmas lights to display solid colors advancing one degree a second and thus repeating every six minutes. New recognizable colors show up every 30 seconds or so except in psychologically similar greens. wikipedia 
A perl script runs in a screen job sending color codes to each of fifty bulbs with short, throw away programs.
See Txtzyme
Last year's favorite program was accidentally left running writing a random color to a random bulb once a second. This was quickly erased with this year's full-string blasts but the flicker of exception made a nice counterpoint to the creeping color evolution.
The progression from blue to violet had the unexpected effect of looking like blue with red sprinkles. This came from the chromatic aberration of my eye glasses when viewing off axis and the pointillist plastic diffusers that make small leds look like large outdoor Christmas lights.