I imagine there are lots of uses for Story Dice, but our favorite use is to hold family story-telling contests. When we are in the car or at a restaurant, we will roll the dice and each member of the family takes a turn telling a story. The rules are that the story must mention every symbol in the throw, and the story can't be longer than a couple of minutes. Then we vote on who told the best story, and the winner gets something like a dollar, or a bite of everyone else's dessert, or some other similar reward.
Story Dice would be a useful tool for writing exercises, too. It's $2 in the iTunes store.
Just for fun, make up a story using the symbols above and post it to the comments!