Subversion is a version control system like CVS (but much better) that I
find to be a pure godsend for jointly authoring anything.  It lets everyone
work on any piece, automagically merging changes when it safely can, or
asking for manual intervention if unmergable changes are made.
  How to access our repository for project "ssaexplore":
  1. Get a subversion client (comes with cygwin/linux, or for other OS's:
     http://subversion.tigris.org/project_packages.html )
  2. Run this (all one command):
     svn checkout svn://yootles.com/home/dreeves/svn-repos/ssaexplore/trunk/
        /path/to/local/copy
     where /path/to/local/copy is wherever you want to store your copy,
     eg, ~/projects/ssaexplore
     NB: it will ask for username/passwd.  Your username is what's left of
     the @ sign in your email address.  Password is the same.
  3. edit the files to your heart's delight
  4. Run: svn update  to get the latest changes from others
  5. Run: svn ci  to checkin your changes
  6. Run: svn status  to see what you need to checkin
  7. (Optional) Learn more with the excellent, online Subversion Book
     (svnbook.org), or run:  svn help