Ben will be back I'm sure but I think it's his nap time....
He may be using some different tools (which I'd love to know about) but many of us use FireFox, FireBug, and YSlow, a plugin for Firebug.
Firebug
is a web developers best friend. It is a powerful addon for the popular browser
Firefox.
It allows you to inspect any element on a page and edit it...live. This proves to be a powerful feature when debugging a site or even adding new elements, without the laborious task of change, save, refresh.