I've dragged this idea around for about 5 years, and in fall 2010, I've finally gotten around to actually building it (just in time for Halloween). It mainly consists of 2 high-torque servos, a small gas burner (for ignition) and a travel spray deo stuffed into a ceramic pumpkin, along with some aluminium L-profiles and a ton of hotglue for support (see image on right). The entire setup is controlled from my laptop via an Arduino clone (ATmega8 with V-USB servo control firmware).
P.S. Sorry about the cheesy metal soundtrack, that was the best I could find on Youtube :-)