A 3d environment (VR-headset with Tom Cruise-style-swiping, or Doom-style with WASD navigation) would be cool, one could be "in orbit", observing the system, watching the nodes and their interactions, and pause and see what messages they're passing to each other. How about time-travel-debugging to allow rewinds too!

As a bonus, porting Doom to it should be "trivial".