Can adding an element of fun, change behavior?  For commuters in Stockholm, it did.  To encourage more people to take the stairs than the escalator, Volkswagen Sweden anonymously transformed subway stairs there into a giant piano keyboard.  As commuters climbed up and down, they were delighted by the sounds of actual musical notes (watch the video).   Stair traffic rose 66%.  Later, Volkswagen revealed they were behind the experiment and a campaign called the Fun Theory.  According to BusinessWeek (11/2/09), the “campaign will next feature Web ads that ‘link the projects to our environmentally friendly cars,’ says Marcus Thomasfolk, VW Sweden’s head of communications.”  How can you inject fun to engage consumers with your brand?