The Texture Switch Node and Polygon Islands
Earlier I made a video explaining how to use the new Texture Switch Node and Particle ID channel in Mesh Items to specifically point images to various meshes. You can watch that video here if you haven't seen it yet (it may be a good idea to watch it first).
In this video we use the Variation Texture node in conjunction with the Texture Switch node to randomly apply images to polygon islands within a single Mesh Item. It's a very powerful and efficient way to texture.
Here's a simple assembly for you to download so you can see how it works.