Emacs Lisp hack for sharing buffers across a network. Several users can all see the same buffer, but only one at a time can edit it. The others see the changes happening.
The server part is written in Erlang and so it needs the Erlang runtime to be installed. The client part is pure ELisp.
Current version is 1.1, and works but is fairly primitive. Developed on Emacs 20, believed incompatible with XEmacs in some small ways.