The Firebug Web Page Debugger, Firefox versionmore info
Firediff is a Firebug extension that tracks changes to a pages DOM and CSS.more info
List elements for each CSS selector, trial CSS selectors by typing them in.
Allows exporting data from the Net panel.more info
View and manage cookies in your browser.more info
Easy access to Dojo features: list dijit registry, and inspect visual widgets, view and breakpoint connections and subscriptions.more info
Log to your Firebug Console from PHP.more info
Extends Firebug's activation model with advanced features.
Test Driver for Firebug itself, useful for extension authors.
Pixel Perfect is a Firefox/Firebug extension that allows web developers and designers to easily overlay a web composition over top of the developed HTML.
Edit your css with FireBug and let cssUpdater update the corresponding property and value in your css source file. Pixel push with ease!more info