I would like to suggest/restate a couple of ideas for PvP combat. First, perhaps we should make Diersville and Gravestown designated PvP areas. They're broken up with lots of cover, pitfalls, and zombies, so they make for interesting battlefields, there's one on each side of the map, and they're large areas that allow for a bit of cat and mouse. Also, neither of them contain much for specialized loot. There are no gunsafes, munitions boxes, wall safes, etc. There's just standard loot you can get anywhere. Thus, it's not a crisis for players to have limited access to them (specifically, limited to whether they're willing to fight). Just a suggestion.

I also agree with Spider that supply drops seem like they ought to be prime PvP areas. I know racing for supply drops is always when I feel the strongest urge to shoot other players. 

Finally, I agree with Cmonster that groups and individuals ought to be able to arrange wars and skirmishes between themselves. For instance, if the Grim Fortress (Me and Wisengrim) went to war against Cookie Castle (Cmonster).