Here's what I would like to do. I want to create a story that branches out in a variety of different, unexpected ways. I don't know how realistic it is, but that's what I'm aiming for. Hopefully, at least one thread of the story can make a decent number of hops before it dies out.
If you are one of the carriers of this story virus (i.e. you have been tagged and choose to contribute to it), you will have one responsibility, in addition to contributing your own piece of the story: you will have to tag at least one person that continues your story thread. So, say you tag five people. If four people decide to not participate, it's okay, as long as the fifth one does. And if all five participate, well that's five interesting threads the story spins off into.
Not a requirement, but something your readers would appreciate: to help people trace your own particular thread of the narrative, it will be helpful if you include links to the chapters preceding yours. Splotchy