While I was in London over the weekend I found some randomly placed Street Pianos (turns out they are part of a big project of 50 pianos placed around central London). Normally when you're in London everyone keeps themselves to themselves. If you talk to anyone you don't know you're considered "weird" (or maybe that's just me). The addition of a piano, and someone who can plonk out a half decent tune on said piano and complete strangers start to talk and socialise with each other.
This is just what happened at Monument on Saturday evening, strangers stood around listening to few random tunes on the piano.
A simple, but brilliant idea. Check out the website and go searching for a piano near you!