This is my suggestion: Add a world like nether/aether/mining that has creative. Wait what about inventories? MultiInv is the answer here is the link http://dev.bukkit.org/server-mods/multiinv/
Um, no new worlds, they are dealing wih serious lag right now and they probably will not want a new world yet.
Jw. As in the sep inv, make it creative so that aether is awesome. Or give captains pnly creative. XD
Creative is a bad thing, if you want creative go to a creative server. This is an economy server and it will NEVER have a creative world.