How about the ability to make balloons, perhaps with bubbles and helium gas, that could be written on and would float, anchored to the ground. These could be used to announce directions to parties or other temporary art installations.
I see this an an alternative to paper notes: more flashy and shorter-lived. They could even be imbued as teleportation scripts, with the balloon lifting the player out of the current street and dropping them in from the top of the destination street (a la Mary Poppins).