This week's Strange Horizons
story is pretty interesting.
There are these "Saints" who come into town one day every year. I'm not sure about the selection process, but some people are designated to wait out for the saints, while the rest of the town goes into hiding. The Saints will possess the people for the day (the Saints actually have physical bodies, so I'm not sure exactly what goes on), and they go around the city doing random things. Painting stripes all along one street. Hanging musical instruments all around one area of town. Blocking off one little area in front of someone's shop and filling it with water and carp. All sorts of little guerilla art things. No one touches them, but they don't always last very long. Pretty neat.