I never understood why nobody has built a documentation webapp where you just enter the SVN/CVS/GIT of a project and the webapp checks out the code onto the ser

I never understood why nobody has built a documentation webapp where you just enter the SVN/CVS/GIT of a project and the webapp checks out the code onto the server's backend at a fixed internval then generates documentation from a standardized commenting layout, kind of like doxygen but more social. It could be neat, you could even have the app merge user submitted comments or changes to documentation (submitted via the web-app) back into the code documentation in the repository. Maybe set a convention where you create a DocApp folder for pages, all synced with the online webapp. I hope this is what Nodata is working towards.