[the.miler]

My Vote: Use Subversion! You have to set up a server, of course, but otherwise it is very convenient. Not just for CAD, but for everything that you need to be able to revert or share. We use it for the CAD files, software, documents . . . everything.

For those who can't use command prompt, there are lots of graphical interfaces you can download. For Windows, TortoiseSVN is very good.

It's a pretty nice system; you download and frequently update your own copy of the repository. You commit your changes to the main copy on the server that everyone updates from. Of course, if more than one person is working at once on the same file, whoever commits first wins. In that case, whoever loses the "commit race" has to revert and try again!

You can avoid such heartbreak by staying in communication with people and splitting up the work. We used a Google doc as a "logbook" in which people signed in when they started working and indicated what they were working on.

Read the SVN Redbook for anything I might have missed . . . I hope this helps.