It would be cool to be able to set a token to "invisible" so that only the GM and that player can see it. When an enemy goes invisible, I can just move it to the GM layer where only I can see it. But if a player goes invisible, we give it an invisible marker to note this, but everyone can still see it on the map. Which, unintentionally leads to players trying to act around that token, like not dropping an AOE where the invisible is, forgetting that you don't actually see that person.