People already hate creepers because they destroy their buildings. What about a mob that loves eating redstone? I don't know why, but I imagine a mob resembling a crab (maybe because it's red like redstone). They would be very weak and only spawn in certain places. Maybe you could tame it and then it would only eat redstone that was placed by other players? And since it would fit through 1 block gaps, it would be easy for it. It could also climb walls like spiders.
My apologies to Mumbo Jumbo if this ever gets added into the game hehehe