In case you haven’t seen these viral videos from Volkswagen, they make an interesting point about change. This experiment attempts to show that people are more likely to change their behavior if it’s fun to do so. Hardly, scientific, but they are clever and inspiring. This video shows how people are more likely to take the stairs vs. an escalator if you make the stairs respond like walking on piano keys. Also a good reminder on balancing sticks and carrots, often the using a stick (punishment) as a form of motivation seems easiest, but offering carrots (incentives) can get better results.
Next, people are more likely to slow down if they can receive cash from those who speed via a lottery. Frankly, I think this one has less to do with fun and more to do with the power of financial incentives.
Finally, there are more ideas for improving recycling and bin/trash usage at http://www.thefuntheory.com/