This a simple chat application developed on nodejs.
node.js(Installation instructions)http://howtonode.org/how-to-install-nodejssocket.ioexpressjade
Visit app on heroku http://dreamchat.herokuapp.com/chat
Browse to http://localhost:3000/chat. Start with entering a user name. Open multiple browser windows/tabs each with a different user name and chat away and see how the messages get relayed.