The Kite boat project
I have been following these guys (and some others) for some time: project kiteboat.
Kites have long been an interesting means of traction, not only can they "make" their own apparent wind (by figure eighting), but their force vector is always upwards, not pressing the boat in the water but lifting it.
First have a look at some of the pictures below, at their website, at this youtube movie and their youtube channel.
When you are still interested maybe look lower down on the page some contect from the pioneers of kite sailing.
The jacob's ladder project might interest you, when large kites did not exist, you had to use a large number of smaller ones.
When speedsailing was still for crazy amateurs/inventors