From SWEC Software:
StoryLink is an app that allows you to create stories with other users around the world. Each user has the ability to create a story or add to a story. With each addition you can add 500 characters and direct the story in any way you choose. Watch as your story ideas change and take new form as others contribute to your ideas. How will the story end; no one knows. StoryLinkLite allows only reading of stories, while StoryLink allows for creating new stories and adding to existing stories.
This is the free version which will only allow you to read stories.