For years I've had an idea for a shot I wanted of a revolutionary war cannon. But it wasn't untill recently that I've had the necessary equipment to make it happen. My idea was to take the shot from the front, and just to the side of the gun. The men who fire the gun all wear ear plugs, and are standing behind the muzzle of the gun, but I wanted the camera to be in front of the gun. Therefore the only reasonable way to do it was to set up a remote.
I set up a body with a 12-24 lens at about five feet to the left and two feet in front of the end of the gun. I racked the lens out to 12mm and fired the camera remotely via pocket-wizard. It's hard to determine the exact second a cannon will fire on any given shot. The man firing the gun is lighting a small bit of black powder that travels down the touch hole and ignites a larger charge in the breach of the barrel. Luckily it only took two firings of the cannon to get the timing just right to get the flame coming out the touch hole and front of the gun.
EDIT: I've also posted a video showing all the pictures from the two firings.
You can learn more about this cannon and the men who fire it on the 2nd Pennsylvania / 43rd Regiment of foot website.