This week, we're thinking small – from microscopic to 140 characters to a couple hundred bucks. Guests include: Peter Sims, who argues that people at the top of their game – from Mark Zuckerberg to Chris Rock – aren't afraid to make little bets; Deb Roy, Chief Media Scientist at Twitter, describing how social networks are changing everything from news to politics to us; Christina Xu of the Awesome Foundation takes us into the world of micro-finance. Plus, a little product that became big business and a one dollar microscope that could change the world.