There are 2 versions of this Websocket demo. Both use the socket.io library http://socket.io/ (on client and server).
Each new client is assigned the next available shape/colour. Clicking or touching the page will trigger an animation of that shape/colour combination across all clients. All connected clients are shown as a list of shapes, with the current clients shape (i.e. 'your shape/colour') enlarged.
Each new client is assigned the the next user id. Enter messages and click/touch 'Send' (or press Enter) to broadcast the message to all clients. This works just like a normal chatroom. All connected users are shown as a list at the top.