I would like to see a destructible/indestructible element that lets ALL elements pass through it, but removes paint as they pass through.
Uses: Painting explosives, without changing the color of the explosion. you could encase it in a thin layer of this new element, so that you could paint the explosive without throwing off the explosion colors.
Might be a few more, but I'm not sure. I know this is only one MINOR use, but this is just an idea. Don't flame.