Hi
This is just a modification of Jon Seagull's script to randomize poly IDs on an editably poly, but you can choose the number of adjacent polygons it randomizes. Meaning, that it can randomize groups of polygons and not just single polygons. Very useful with polys with lots of similar elements, like Ivy Generator and trees, in which you randomize the elements to have different kinds of leaves.
Hope you find it as useful as I did
http://rapidshare.com/files/259027731/poly_randomIDs_eli.mcr