A few days ago I uploaded a new version of StoryAwaits containing a new story type: Chain Stories (YAY!)
Chain Stories are stories you can write together with your friends, each person can see the last part added to the story and then can add the next one.
Once you add a part to the story you get a link that you can share with the person you want to continue the story.
I have plans on adding more features to the Chain Stories in the future.
You can see a list of the chain stories you started in your profile.