What does it say about the Atlanta area that ZOMBIES have become such popular subjects for the arts? The past year saw the national release of the Atlanta-filmed horror flick The Signal, in which a mysterious transmission turns couch potatoes into violent lunatics (not technically zombies, but close enough). Dad's Garage Theatre produced the world premiere of the stage musical Song of the Living Dead, featuring musical numbers about brain-eating undead ghouls; and zombies crashed a prom in the high school horror-comedy Dance of the Dead filmed in Rome, Ga., and due on DVD in October. Maybe no one who's ever driven in local traffic would be surprised at the proliferation of creatures that embody both mindlessness and rage. At least they're appearing in creative examples of mindless rage.