FireQuery: Firebug Enhancements For jQuery
FireQuery is a Firefox add-on that extends Firebug with new jQuery-focused features.
It adds extra functions to the HTML tab like showing embedded data elements & event handlers inserted using jQuery.
All the jQuery expressions are presented in Firebug Console + DOM inspector and elements in jQuery collections are highlighted on hover.
Also, the jQueryify bookmarklet is integrated into FireQuery which makes injecting jQuery into any website possible.