Remember Big, the movie with Tom Hanks about a kid who grows into an adult's body but keeps his 12-year-old mind? There's a great scene where he and Robert Loggia, playing the CEO of a toy company, play Chopsticks on a big-ass piano keyboard built into the floor of a toy store in New York.

[youtube http://www.youtube.com/watch?v=rKrZiddRphw&w=560&h=315]

In Stockholm, a group of folks took a similar approach to encouraging people to climb stairs. They installed a working keyboard on a flight of steps at the Odenplan metro station, and soon people all but abandoned the escalator in favor of banging out surreal tunes on their way to the street.

[youtube http://www.youtube.com/watch?v=2lXh2n0aPyw&w=560&h=315]

It's part of the Fun Theory, a program by Volkswagen to see if you can change people's behavior by making things fun. So, walking up stairs is more fun when you're stomping on a keyboard. Throwing trash into a trash can is more fun if it sounds like it's falling into a deep pit. Recycling bottles is more fun if the recycling bin is an arcade game. Basically, it's gamification in the real world.