Four LCDs on the main machine (G5) that runs the applet and displays what is happening in all rooms. Two screens on the secondary machine (G4) I have three video cards in the G5 with two outputs each, and I have one more empty slot on the bus, so I could pretty easily add four more LCDs if I thought that would be helpful, or sufficiently cool.
eight-core Power Mac driving five monitors in portrait mode. The portrait mode orientation is really nice for getting lots of lines of code visible at one time.