I've opened up a poll over at Monster By Mail and I'm soliciting feedback from users as to what theme they would like to see in an upcoming installment of MBM. Why don't you head on over there and use the poll on the sidebar.
BTW, Zombies are still available! I am only doing them for a lmited time and then onto something brand new. So if you've been on the fence, now would be the perfect time to snag one up.