Squeak, its a Swiki!
Martin Doherty of Ultralab (1990-2006) and myself have been working hard on finding a collaboration tool which lets many people contribute to the same document over the web to collaborate to together and edit the same document online.
We found Squeak Swiki very easy to install and use on our own server after Swiki.net just stopped working overnight. Swiki.net allowed anyone to set a Swiki up on the Swiki.net server. Squeak Swiki has allowed us to download and install our own version on our server which Martin has built into a community of pages which can be edited, added to and debated in.
Will update as we use this way of collaborating and planning together, as part of the Executive Learning Workgroup project with Oracle and the Business Schools before we migrate into Oracle Collaboration Suite for a project together, once our OCS installation is up and running.