I helped 3rd graders write stories at http://storybird.com/ yesterday. They had been on the website once before and were anxious to create more stories. The author selects pictures and adds text to create the cover and pages. A free account is required to save and publish the books. After they have been saved, but not yet published, books can be edited. This is nice because it is not necessary to finish in one session. Students can also invite someone to collaborate on a book via e-mail. Once a book is published, it can no longer be edited, but it can be deleted by the author. The author has a choice of keeping a book private and accessible only be e-mail invitation, or making it public.
As the students were working, I thought about reading how publishing students' writings for a larger audience than their teacher or classmates motivates them to do their very best. I could see this was happening.
Today, I decided to give it a try and am now a published author. You can read about Max the monkey here: http://storybird.com/books/max-the-monkey-learns-to-make-friends/ Also, check out some of the other stories by clicking on the Read tab.