I tried this on my way into work this morning:
Ride towards zebra/pedestrian crossing. Spot pedestrian loitering, showing some intent to cross.
Come to gradual halt before you reach the crossing. Nod, even smile encouragingly at pedestrian to let them know you have actually stopped for them, and they can actually cross.
They get to other side of road.
This actually becomes rewarding as the pedestrian is first astonished, then normally thankful, and more often than not, you get a nice smile.
Don't go overboard though. The pedestrian does not want to be hugged or kissed.