Not in any particular order…

Nikola Tesla : Greatest technology inventor in modern times.  Created the AC electrical system every single house in the world uses.  Spoke about the cellphone and created one of the best designed electric motors.  We have yet to discover and understand most of his engineering notes he took asof today in the year 2011!!!
Nikola Tesla : Grestest inventor contributor to modern society.  We use his inventions every single day a century later.