I would actualy like to see something like this in destiny. Like next halloween make a special patrol mode in the cosmodrome that has you fight zombies with guns only and search for weapon parts(special kinds used to make event weapons) and like skeletons and all kinds of crazy un-dead themed enemies. Make the public events like massive hoards of zombies that flood into an area from all spawn zones and even the areas where you enter the zones from have hoards of zombies pouring from them trying to overwhelm you. And finaly have a community focus point were as zombies die it fills up a percent meter and as different checkpoints are reached it unlocks new goodies like ships,shaders,emblems, special skined versions of popular weapons, sparows, armor, etc...
If bungie ever made this an event, i would have trouble putting the game down till the event ended.
Bump the shit out of this post if you want bungie to see it.