i found a nice article on Londonist:

Interview: Liz Akers of Team Nice

Liz, one day on the way to work, on the bus saw a lady giving the driver a hard time. At the next stop the driver didn't stop for someone running for the bus. Seeing how bad feeling gets passed around she had the idea of "passing niceness around London" in the form of "nicetie token".

Once you get one (for doing something nice) you can go to Team Nice and join. When you see someone doing something nice, you give them the token. See, passing nice around. (:



Also in the article is a link to "I'm up for a chat on the tube", wear a badge on the tube/bus/train to indicate you are "up for a chat". i bet some nice friendships have come from that.