http://www.codingmonkeys.de/subethaedit/

editor for MacOsx based on ZeroConf.

Contains solutions akin to RealTimeWikiDesign, sans the Wiki concept.

I recently had the joy of using SubEthaEdit at a conference with half-a-dozen other people. The results were amazing. We used SubEthaEdit to collectively take notes, organize questions, and keep in-line commentaries. The result was a complete set of notes on the whole conference complete with a bunch of related data, links, and conversations. We even used the very bottom of the document to organize lunch and other events. It completely changed the conference for me. I highly recommend the use of it or similar products (along with an mDNS discovery tool) when in such situations. -- DaveFayram

MoonEdit, QuantumPairs and MultitaneousEditor seem similar.
----
Oh My God it's REALLY cool for PairProgramming (remotely). That and they don't add a hundred bells and whistles, just the stuff that is really needed. Watching an effective group use this tool is quite amazing. I frequently pair up with people to do web work in it. One person does content, another CSS, etc. -- RyanDavis
----
The name is an allusion to the HitchhikersGuideToTheGalaxy.
----
See also GobbyEditor for a free (OSS) cross-platform alternative
----
CategoryCollaboration, CategorySoftwareTool, CategoryTextEditor