Hey I remember this from aaaaaages ago, hopefully someone has it still! Basically it was an include for three arrays (red, green and blue) each with 256 entries (or there about). Combining the return from these arrays would give you the colour at point X of a looping rainbow strip.
ta!
EDIT: Naymind, made a simple one myself :D
ta!
EDIT: Naymind, made a simple one myself :D