What needs to exist is a system that's akin to this site's functionality that could be used on a personal or university server and allow multiple people to contribute (via password-protected entry to the web-site) together to a notebook page which contains $\LaTeX$ markup and does it in a clean fashion.
Perhaps the newer incarnation or instantiation of MO being tested on alpha.mathoverflow.net would allow for something like "private question pages" which are invitation only and could be used as an adjunct for white-board like functionality while the participants also use a telephone or skype or any other tools for instant collaboration. This technique would also allow for asynchronous updating by the collaborators if they happen to be living/working in different time zones.
