Roll your own.
Or wait for Boeing
Go French
Go Russian
http://www.treehugger.com/2007-12-05_103243.jpgAlthough tremendous fuel saveings are possible for very heavy freight haulers , I see these as dead end concepts simply because they must stay low most of the time .
There isn't any good way for these to cope with heavy weather or very high waves.
If you want to see Mother Nature makeing use of the concept watch a pelican fly for miles with little effort inches above the water, but Pelicans don't mind riseing and falling with the waves or sitting out a storm.