Here's a suggestion:
I understand this would be much, much later down the road... but what about a kind of "zombie kill squad" or a group of (at least 6) survivors who randomly come through to massacre zombies, say some cool s*** and then bounce.
You can't recruit or join them. You can attack them, but you'll die 99.9% of the time - because they're badass.
Basically, their purpose in the game is just as a badass crew of zombie killers.
Maybe have an option to control how often they appear in the game. Kind of like the meta events. All the meta events in the game so far (and the Sadistic AI Director) are designed to kill you, or at least scare you half to death.
The Zombie Kill Squad could be like a good meta event option.
