I'm not sure how my wife discovered it, but we have learned our cats are terrified of ghosts.  Or at least ghostly sounds.  If you walk into a room in my house and let out a ululating ghostly cry, any cats anywhere in the room will suddenly reveal themselves and bolt for the door.  Doesn't even have to be loud... they just freak out when they hear it.  This has become a useful tool for dealing with a cat that is getting into something she shouldn't.  Instead of scolding or trying to chase the cat away we just go "WOOooOOOooOOOooOOO!" and the cat will stop immediately with an extremely hilarious expression and then vacate the premises.

Our dogs remain unimpressed.