Winan steam gun
The Winans Steam Gun was a departure from the typical gunpowder based weapons common to the era. The weapon used centrifugal force and springs to propel shot at 250 rounds per minute. The major advantage of this contraption was that it was not as unreliable as conventional gunpowder since it could continue to fire even when wet. This gun is noteworthy solely because of its unique firing method. This weapon truly was a departure from the norm and an attempt at something new. Although this weapon hardly affected the course of the war, it is still noteworthy due to the amount of media attention it drew.
A very unusual weapon, the harmonica gun was developed to provide users with a way of firing multiple shots without reloading. All that was required was that the user simply push the magazine from right to left after a round was fired. The simple impracticality of the weapon, especially the difficulty found in holstering it, led to its obsolescence at the hands of the more popular revolver. The pistol was patented by French inventor J. Jarre and most prominently manufactured by Jonathan Browning.
The Ketchum hand grenade was a cast iron, three piece explosive made to explode on impact. However the grenade needed to land on its nose in order to detonate, as a result the Confederate soldiers quickly learned to catch them in blankets and lob them back at the Union soldiers. Although this explosive new weapon was not very effective at least for the Union, it influenced the future of designs of hand grenades.Designers realized that grenades that needed contact to explode were largely unreliable and so move to the timed explosive approach.
The gatling was the first successful early rapid fire weapon ever created, developed by Richard Gatling at the beginning of the revolutionary war. It consisted of a rotating barrel that was cranked by hand in order to fire the rounds; after each full cycle, the gun would automatically spring-reload itself. This weapon was chosen because this a perfect example of unique American innovation in a time of desperation and war. The gatling gun served as the predecessor to all modern machine guns and automatic weapons. 
The H.L. Hunley was one of the first ever “working” submarines crafted by the Confederacy in order to hopefully run the Union blockade and stealthily destroy Union ships. The term “working” is used rather loosely as it sank thrice, killing all crew on board each time (including its maker), and only managed to scrape together one kill. This craft was a novel invention of the period spawned out of the desperation of the confederacy and served as a stepping point for all future submersibles.