Swings, installed publicly in urban and natural settings. The amazing feedback we got from people via interviews or emails was incredibly positive. Kids loved the but the more important impact was on the adults who used them. They were instantly transported back to a better time and lost themselves in the moment. Pure and utter unadulterated joy. The happiness that sprung up in them was palpable and filtered down to others as they carried on with their day. It's contagious.

So we've already done this on a small scale. Seven swings strung across the city at the cost of about 150 bucks. The cost is mostly in the rope and we learned ideal heights that would save us on rope costs the next time around. 1000 dollars would finance 100 swings across the bay area spreading pure and simple joy from a forgotten source.

Here is the video from our first experiment, which is guaranteed to bring a smile to your face:
http://www.youtube.com/watch?v=373kAws3Mug&feature=player_embedded
http://www.woostercollective.com/2010/06/ohsanfran_happiness_project_10_swings.html
http://mattgartland.com/greatness/oh-san-francisco-swings/