What about an event deck? Before play or perhaps during, draw a card (not to often though). might add, rain, fire, lights out, lockd door or something else to the game.. Even though I belive that LNOE is overdooing the random events occuring during a game, the element of surprise is a must for all good zombies themed games..
Another thing I would like to see is more gory rules.. Like the feast rule in All things Zombie..
Subway sounds cool though, a couple of scenarios focusing on activating the subway train before travelling with it.. Everyone who played Resident Evil, knows that you can't travel for more than a few seconds in a sub or any kinda train, before something big and nasty jumps at you...
But as I wrote ealier, with the map editor and a bit of photoshop knowhow I can't see why we can't create the subway ourselves.. Then the rest is gametesting..