One minute, Dennis Crowley, the co-founder of Foursquare, was building a little app in a New York City coffee shop, and the next he was being wined and dined by every VC in Silicon Valley, being offered hundreds of millions of dollars for his young startup, and seeing the valuation of his company head towards a billion dollars. Crowley takes us through the tumultuous, breakneck, insane ride of running a startup.