Saros brings multi-writer synchronous distributed editing to the Eclipse IDE, e.g. for joint code reviews, explaining code remotely, or distributed pair programming -- all also for more than 2 participants; we call this Distributed Party Programming. It includes refined awareness functionality, text chat, and a simple distributed whiteboard/sketching facility.
Eclipse Update Site: https://www.saros-project.org/update-site/eclipse
OCDE (Open Collaborative Documents Editor) is a spreadsheet and rich-text editor, which allows to edit documents with other people. It is developed in XUL and based on XMPP (Jabber) to synchronise documents between different computers.