I found very interesting seeing how Mark Zuckerberg put together the pieces of his creature. Two main ingredients were at the basis: his deep consciousness of what his creature should be AND an ear always open to listen to what people have in mind.
Mark says: “We are talking about taking the entire social experience of the college and put it online.“
Mark had the ability to perceive that “the social experience of the college” can be so fascinated and attracting for people AND the capacity to read the Web and to put online such an experience.
If and when you are really able to have such a clear line in your mind and simultaneously take in consideration the needs of your users then, I think, you reached the “secret” for your success.