TL;DR: Since a few months Debian also hosts a Gobby server. You can find it at gobby.debian.org. To use it, install gobby-0.5.
Gobby is a realtime collaborative editor, much like Etherpad, but as a standalone desktop application. (It's also open source since the beginning.) It resembles gedit somewhat. In retrospect plugging into gedit would've made more sense than to develop yet another editor.
Sadly there's a catch: Gobby had multiple iterations at getting its protocol right. So there are two incompatible versions: Gobby 0.4 and Gobby 0.5. But to confuse you, Gobby 0.4.9x is currently called Gobby 0.5. The lead developer wants to get self-hosting (i.e. the one-click creation of a server) back into the application before he calls it stable.
So to use the aforementioned server you need to apt-get install gobby-0.5, invoke gobby-0.5 and type gobby.debian.org into the "direct connection" field in the lower left bottom. This will give you a document tree on the left, where you can create new documents and folders. Please don't be destructive.
If you have a problem, if no one else can help, and if you can find them, you might contact the admins at admin@$service.