If you are a marketer, chances are that you have read about the holy grail that is viral marketing, the campaign so stealthy, so clever it takes off in exponential fashion, inspiring customers around the country to engage with your brand. Winning examples include Burger King's subservient chicken and CareerBuilder's monk-e-mail. So why haven't you set aside a budget for viral marketing? In short, it is hard. Hard to develop something so brilliant that it resonates with vast numbers of people. Hard to identify the right set of key influencers. Hard to promote without seeming overtly commercial.