When you working in a web application project with rich client feature for example like using full Extjs component, you must be dealing with a lot Ajax request, you must be want to know what the server response so in local development in different kind of web browser I always using these tools.
Firefox
You can use firebug for firefox addons for seeing ajax request that sent to server and see the server response, the advantage using firebug than the webkit inspect element is you can see the server response as a simple text or as an html, but on my firefox sometimes it got some error (nothing wrong with the server but server response not displaying on firebug). After you installing firebug restart the firefox and click on the firebug icon on the right bottom.

