You have probably seen people sculling (using a single oar off the stern of a boat) in movies or the like. I know I have never tried to actually do it.
Well, Guy Capra has invented a little widget to make the somewhat tricky oar handling "automatic".
Check out the video and a detailed article at Duckworks.
The Scullmatix is a simple device to make sculling a boat almost automatic. It is made from 1/8" stainless steel plate and has two 5/16" SS carrage bolts with wingnuts. It weights just under 2 lbs. It is very robust – it should last several lifetimes.