Trust the Minecraft community to make a mod of a mod. In this case they're currently building a version of DayZ, the brilliant persistant Arma II zombie mod. The more you think about it, the more ...
Check out the list of the best mods for the Minecraft Pocket Edition, including, 99 Night Forest, Mowzie's Mobs, and more.
I've been playing the MineZ public beta, the DayZ inspired, server-side Minecraft mod that chucks 150 players into a zombie-infested open world and expects them all to survive and play nice together.