The Neverending Tale is a web-based tool allowing students to collaborate on creative and expository writing. Students choose their own path through a story line. Each page contains text and a list of choices to follow. Each choice branches off into a new page, with its own text and choices. The outcome of the story depends on what choices the reader makes on each page. The program has been shown to be most useful for students in grades 4 through 8.
The Neverending Tale [1]
This is another good example of non-linear hypertext writing. While it might not contain good writing per say, I think the concept is quite cool.