A Materials Library

This one hit me the moment I examined the materials featured in the Artist Point Example Worlds. Once you start making materials, you really want a place to save them for future use, saving you the trouble of recreating materials over and over again, or trying to copy and paste materials between world files. Like macros, and even Example Worlds, you want to be able to preview materials to make sure they're right for a given scene before you load them, and unlike Blueprints, Materials are just individual devices you are likely to grab one at a time.