I was looking for a fast growing tree and found the Empress Tree. I could not really believe it when it said they grow up to 15 ft. a year... yeah, right...
BUT... it does! We planted one of ~ 2 ft. height this spring, I believe it was May, and now it's ~ 11 ft.!!!
So... if you want a really fast growing tree...
http://www.fast-growing-trees.com/EmpressTreeT2.htm