I already opened a suggestion thread about this topic: <a href="http://community.roll20.net/discussion/102/invisible-tokens#Item_3" rel="nofollow">http://community.roll20.net/discussion/102/invisible-tokens#Item_3</a>
I thought it would solve what I want to do, but it does not.
I would like to set a token as invisible. Moving it to the GM-Layer does not solve the problem. When it is on the GM-Layer I need to switch to the GM-Layer when I want to move that token and switch back to the token layer to deal with the visible tokens. For dealing with invisible creatures in a fight, this is not a very comfortable soloution.
Additional, I would like to set a visible list on those invisible tokens. That means, I would like to set that token visible for specific players.