If there's one scientist in history that you can safely call mad, it'd have to be Nicola Tesla. His passion of wireless technology exceeded that of most people's imaginations, to the extent that he claimed he could communicate with aliens. Despite his questionable mental state, Tesla is praised for developing AC power transmission, and the pioneering of radio communication.
But that's not all Tesla is known for. He liked to show off, with what we now know as Tesla coils. Tesla coils use very high voltage to produce vibrant sparks between a capacitive ring, and a grounded object. They're usually large devices powered by hot and heavy transformers, just like in the spark rendition of Sweet Home Alabama.
Tesla coils are pretty neat to look at, and even better when they're used to play music. What could possibly make them more awesome? How about a Tesla gun!

The chap pictured above is Rob Flickenger, an eccentric scientist who happens to really like the combination of Tesla's technologies and weapons. He states that his inspiration for the Tesla gun was the graphic novel 'Five Fists Of Science', which portrays Nicola Tesla as a superhero who dual-wields Tesla guns. The cool thing is, this gun actually fires!
You can take a look at this menacing weapon in the video below, in addition to an interesting overview of Tesla's life, and an insight into how the pictured Tesla gun was made. There's also a neat summary at the creators website.