The only part of this that requires forethought is naming the additional images to go with the base image, and I suspect that's a big hurdle for some people.

I could imagine an interface that allows you, after identifying the product to associate with, to browse and select a random image (or group of images), renaming it to fit with the product's base image before ftp'ing it to the server. I'm not sure if this is practical to do from within admin.