Norhing I've done, yet, but here are some or the thoughts from the voices in my head . Probably will need to get a hold a 3D printer, but would be cool to make Packout bases for the fan and whatever your preferred speaker is. I wouldn't mind a nice comfy high-back seat some days, plus swivel.
If that metal hook could extend out and was beefier, you could haul a couple sheet goods on it, though very limited maneuverability.
This would never get OSHA approved, but a scaffolding piece that could attach to 2 sets of Packouts.
No idea where I'd begin, but an alarm running to a dead-mans switch triggered when the stack is tilted back.
Similar to the job-clamp device, something to secure material for cutting. Light weight vises if you will.