Online collaborative writing of LaTeX documents

There are better ways than using email, that’s for sure. You can find a nice review of various collaborative writing tools on LaTeX wikibook:  SpanDeX and ShareLaTeX allow for only one collaborator per project within their “free” licenses.  WriteLaTeX is like EtherPad for LaTeX, anyone who has a link to the document can participate in editing. Unfortunately, it lacks advanced functionality such as version control and cloud support. Very promising project SciGit has not been launched yet.