There are scenarios where refreshing page to see results of your updated code is just too painful. This could be coding a mobile HTML5 app, or inside of facebook canvas.
inspired by jsconsole.com, I have created tool that lets you remotely update HTML/CSS/JavaScript. It uses HTML5 web sockets to do the transfer, so only works in "modern browsers" and runs on node.js server.
Here is the github repo.
This is how you can used it: after setting up your node.js server, put this code on the page you would like to remotely control:
<div id="content"></div> <script src="http://localhost:8083/js/init.js"></script>
And then through the code.html page "inject" HTML/CSS/JS into the remote page.