Gobby is a tool which allows teams to edit the same document simultaneously in real time. We use it at Koumbit during some meetings; and when we quickly need to produce a document without going through the normal revision procedures.
As of this writing Gobby 0.5 is not available directly on mac OS X (The MacPorts installation guide here gives me Gobby 0.4, which is incompatible with Gobby 0.5). We will therefore install a Ubuntu virtual machine with Gobby on it. Set aside about an hour or two for the whole process.
Gobby is now installed on your Ubuntu virtual machine inside Mac OS X.