I separated some functionality from my floor board generator that is more generally useful: a tiny addon that creates random vertex colors for individual faces. One of its use cases is to add some variation in the color or reflective properties for leaves that are generated by ivyGen or my Space Tree addon. Both addons generate a single mesh object that contains all the leaves where each leaf is a single face. Separating thousands of leaves into individual objects just to use Cycles’ per object random number generator is tedious so I thought a better way was to create random vertex colors that can be accessed from a Cycles Attribute node and used to drive for example a hue/saturation node.
I’ve documented it in this blog article (including download instructions)