Meet people at the lights and have a nice chat while waiting for the lights to change. Also, the chance to help out people: I got off my bike to push a man in his wheelchair up a hill the other day as he was struggling to turn his wheels in the wet grass. There was lots of traffic going past but of course noone could stop to help him during peak hour traffic.
Be recognisable, especially if you ride a distinctive bike. I have been recognised by a few people just because of my bike, they have always turned out to be friends of Steven Fleming.