Did you know that two of the Union Army of the Potomac's most inept commanders were responsible for two words that are still a part of the language? The term "hooker" was coined because so many prostitutes followed the army (to make the men happier during their off-hours) when it was led by Gen. Joseph Hooker. The ladies became known as "Hooker's women" and eventually just "hookers." General Ambrose Burnside wore a very unusual semi-beard that was shaved at the chin and throat. His facial hair soon became known as "Burnside's sideburns."

What always strikes me as interesting about the US Civil war is the invention and use of the Gatling gun. It strikes me as a technology that helped the North have an advantage over the south, and I am amazed by how similar it is to modern machine guns. It really does strike me as one of the forefathers of modern warfare. Since the Gatling gun was invented in 1861, it seems to have been just in time! You can read more about this fascinating weapon here: http://en.wikipedia.org/wiki/Gatling_gun

I'll throw in two.  One is that the first "successful" submarine attack occured during the Civil War.  The Conferderate ship destroyed it's target, but unfortunately itself as well during the attack.  Additionally, Confederate General Robert E. Lee wouldn't read bedtime stories to his kids unless they tickled his feet.

There was widespread discontent with the war throughout the South, especially among non-slaveowners. In some areas, discontent reached the point of open insurrection. There were draft riots and bread riots in several major Southern cities, and one region, Jones County, Mississippi, actually witnessed open fighting between deserters and Confederate forces. The Confederacy dealt with these problems through repression, including suspending the writ of habeas corpus, as Lincoln did in the border states of the North. 

http://books.google.com/books?id=DlURqtC7vPQC&printsec=frontcover&dq=Free+State+of+Jones&hl=en&sa=X&ei=oKqpT-mwPMy3twe64OGuAg&ved=0CDkQ6AEwAA#v=onepage&q=Free%20State%20of%20Jones&f=false

Here's one that not too many people know about.  A Confederate raiding ship, CSS Shenandoahwent around attacking Union shipping in the Pacific.  It actually reached the island where I grew up (called Pohnpei now, called Ponape in this link) and attacked Union shipping there.  This is an island that's 2500 miles or so southwest of Honolulu, so we're talking about a naval battle from the Civil War that took place pretty far away from most of the action of that war.