The crowd at a Jonathan Coulton show is as engaging an act as the singer-songwriter himself. Fans dress up as zombies in anticipation of his playful pop ballad "Re: Your Brains," about an undead coworker who is nonetheless professional. They brandish homemade T-shirts and dolls; they boldly engage the performer in conversation between songs. Coulton encourages this behavior, with a savvy marketing plan that turns his work into an open book. His new one, Artificial Heart, drops this fall.