The late 1800s was an interesting time for science and invention. Human control of electricity was in its infancy, and many devices we use today, such as the light bulb, and even radio communication have their roots in this era.
Of course, there were many other inventions that are perhaps less useful in themselves, but led us to a better understanding of certain concepts. The Tesla coil comes to mind, but you might also consider another lesser-known “spark device” known as the Wimshurst machine.
These machines build up charges via electrostatic induction via two disks that rotate in opposite directions. When the charge differential is built up enough, a spark occurs between two conductors. If you’d like to try out this interesting device, the SparKIT version is a modern take on it. This machine uses modern capacitors instead of Leyden jars to store the charge, and the counter-rotating disks are constructed out of PCB segments. Though capable of generating 20,000 volts of electricity, due to its low current capacity it’s safe to use under normal conditions, though electronics should stay away!
I certainly think this outdoes any “executive desk toys” that have come before it. Sure, your boss might have a kinetic sculpture that swings back and forth in perpetuity, thanks to a hidden electromagnet. You, however, will have 20 kV in your cubicle—which everyone will know as your Dr. Evil laugh reaches its peak.