It might not be what you'd think. Thomas Edison's greatest invention wasn't the phonograph, the dictaphone, or even the incandescent light bulb. It was his innovation factory, that later became General Electric, that gave rise to these discoveries. Likewise, Sergey Brin's and Larry Page's best invention wasn't Google's search engine. It was the factory they built that encouraged a stream of discoveries such as Google News, Google Maps, and AdWords, to happen. The transistor and the laser didn't exist because of an individual. It existed because of an organization called Bell Labs. Santa Fe Institute's Geoffrey West points out: "Looking at the great paradigm-shifting innovations that came out of American industry after World War II, things like the transistor and the laser, you realize that the driving force that gave rise to them was the enormously free innovation environment that places like Bell Labs fostered." If you're looking to find the next billion dollar idea, build an organization that fosters innovation.