websockets

http://socket.io/docs/
Creating Your Own Node.js WebSocket Echo Server: http://cjihrig.com/blog/creating-your-own-node-js-websocket-echo-server/
Starting with Node and Web Sockets: http://codular.com/node-web-sockets
Raspberry Pi — Getting interactive using Node.js WebSockets: http://www.jaredwolff.com/blog/raspberry-pi-getting-interactive-with-your-server-using-websockets/