Storymash is a collaborative creative writing community. For authors, it allows several different users to contribute to a story.

Users can write chapters in the same book, allowing for the story and plot to change dynamics. Authors can even earn money based on the chapters they write. Readers are able to read chapters from these stories and vote on their personal favorites. Attached to each chapter is a user forum, where writers and readers can make their comments on the writing seen. Storymash also holds creative writing contests where users are able to compete for a cash prize.
 
URL: http://www.storymash.com/