I’ve experimented with real-time collaborative text editors going back to at least 2006 (starting with MoonEdit). This was precisely the reason I was not impressed by Google Doc’s initial concurrent editing functionality, even though it seemed the world was going nuts about it (not sure what the current state of it is).

I’ve used Gobby for collaborating on plain text documents (content without design). Gobby is an open source desktop collaborative editor and runs on Linux, Mac OS X and Windows, If you want to try it out simply install it then click “Join session” in the toolbar and as a Host fill in “gobby.0×539.de” (without quotes).

There’s also EtherPad, launched in November of 2008, which seems to be the best (both in terms of user experience and depth of functionality) online real-time collaborative text editor currently out there. The biggest difference between EtherPad and Gobby is that the former is a web application, so you don’t have to install anything to try it out (you don’t even have to sign-up).

The company behind EtherPad (AppJet) has recently been acquired by Google, which led to open sourcing of EtherPad itself.

I’ve created a pad that you can use the try out EtherPad (and so I can check up on if anybody tried it out ;-).

If you want to collaborate on more formal documents you might be interested in Abiword’s real-time collaborative editing functionality (video).

For me the biggest disappointment in this area so far has been Google’s Wave implementation. I originally had high hopes, but, and I’m sorry to have to say it, for me right now it’s completely unusable for both communication (chat) and any form of collaboration. I’m keeping my fingers crossed that the situation will improve and wish them the best. Also see the comments from the EtherPad team on Google Wave.

On a side note. Wouldn’t it be totally awesome if you could simply plug-and-play real-time collaboration functionality in for example Geany, the basis is certainly there in the form of libifinity from Gobby though still a lot of work still needs to be done (undo/redo functionality being the major lacking feature).