DivHTTP is a addon for Mozilla Firefox that enables you to run a HTTP server directly from the browser. So it's perfect for testing webpages. DivHTTP creates a widget in the Addon bar of Mozilla Firefox. You need to click it and select the dir and the port number to start the server. Simple and also works.
DivHTTP is a restartless addon, this means that you don't need to restart Firefox to enable it. It's better because you can do personal things (Facebook, YouTube, etc) with the extension disabled and when you're working you can enable it.
This software is recomended for web developers for general pourpose or HTM5 game developers.