Me and my friend Jurgen have bin working on a map called 'Screw the Zombies'. We've recorded how we made it too, so that'll be on our youtube channel. It isn't entirely finished, we're still working on the last things, but it is pretty nice though.
It is a
zombie map, but not with spawners. We've made it entirely with redstone
(my friend did, because I'm not so good with it), so you won't have the
problem of too much zombies anymore. The zombies will spawn in
spawnhouses, with dispensers inside. They will be Zombies, a small
change of a Witch to spawn, and (Wither) Skeletons. It is pretty
awesome, the download will be out really soon.