Maybe once or twice a year I'll just take a few days off and wander around and ask myself, if I were starting from scratch today, and I weren't running Facebook, what would I build? I look at this mobile trend in light of the law of sharing, our equivalent of Moore's law, which states that the average amount of information that a person shares doubles every year or so. Figuring out what the next big trend is tells us what we should focus on.