Atlas Randomizer

This is a great procedural texturing tool that randomly selects a UV spot from an evenly divided grid image. For example, let's say you have an image that has different square light tiles. The image has 6x6 lights in each direction (X & Y). All you have to do is append the atlas randomizer node to your scene, determine the grid divisions (6x6 in this case), and you have totally random UV selection per object instance.

That's just one example. You could also randomize assets as seen here:

Includes:

.blend file with atlas randomizer node group.