"Sarma is a live, over-the-web documentation editor supporting DocBook imports and exports, per-unit (paragraph, title, figure, ...) revision control and handling, and WYSIWYG interface to make editing docs a natural process: you view it and edit it right away. It's written by DaniloSegan as his Google SummerOfCode project."

See at http://live.gnome.org/LiveDocumentationEditing