Piano
I've just been for a wander up Oxford Street and in one of the shopping centres there is a baby grand piano, painted with a Union Jack design and with the words - 'I'm yours, play me'.
So random people are going up to it - picking a piece of music from a selection that has been left on top of the piano, and just playing a song before continuing their shopping. I watched three people do it while I was standing there.
I was tempted to have a go - but I was far too self-conscious and my piano playing is slightly rusty.
I thought it was a nice touch - but sadly I'm also wondering how long it will be before some yob vandalises the piano and spoils it for everyone else.