My brother-in-law, and his father, came across a Toro Flymo. This is a neat little hover-mower. It's gas powered, and uses a single standard 19 inch blade. From what I have been able to look up on this contraption, its especially useful when mowing on hills or inclines. When started, using a standard pull start, the mower hovers about 2 to 3 inches of the ground. It's louder than a standard mower, and significantly louder than most newer machines.
Here's a few photos of the mower.
I also want to just make a little comment about my brother-in-law's junk collection. During the few hours I was there he brought out the Toro Mower, an old power saw (which he gave to me), a scuba tank, spare parts for a kegerator, and a book featuring the city & town layouts from the late 1800's and early 1900's. He's got a pretty good collection.