I am not sure how hard it would be to add this feature, but I think the ability to add decals onto the surface of any model and move it around to any part of the object would be cool and if we can add multiple then that would be even cooler.

That way regardless of whatever texture we use we could always easy add some variation to it, like adding a blood splatter decal to an object with a metallic texture or adding a bullet hole decal to an object with a wall texture. Decals could also be used to add stuff like graffiti or certain icons or symbols you would usually have to create custom textures.