MoonEdit. Ooh…
Cooperative multi-user text editing over the internet. Every co-author can edit the shared document at any time, from any place, and at the same time! There’s no need to send files via FTP or to compare documents when multiple users need to make changes to it independently…Remote text editing without latency. “ME” uses local prediction code – the same technology used in modern video games! You can use a dedicated standalone server to share a whole directory of text files. Remote users can then edit these files using the “me” client – at the same time.
For Mac OS X users, try SubEthaEdit. It’s been around for quite a while. Coloborative editing is great over Rendezvous & AirPort at large gatherings.
http://www.codingmonkeys.de/subethaedit/
Tings are online-gatherings using moon-edit. Ting5 is on Thursday 24th of Feb, 21:00 GMT. See the ting-wiki.