That looks very much like the wingtips on the Airbus 320 and 310! I have wondered if it would work on a sail. Let us know if you see any difference, I think it might need to be bigger though. http://www.jetphotos.net/viewphoto.php?id=264848

The other thing I have thought about was adding vortex generators to the main about a foot back from the mast, for light air sailing.