May 09
Firebug - Firebug integrates with Firefox to put a wealth of web development tools at your fingertips while you browse. You can edit, debug, and monitor CSS, HTML, and JavaScript live in any web page.
Web Developer - The Web Developer extension adds a menu and a toolbar to the browser with various web developer tools.
FireShot - FireShot is a Firefox extension that creates screenshots of web pages.
ColorZilla - Advanced Eyedropper, ColorPicker, Page Zoomer and other colorful goodies…
YSlow - YSlow analyzes web pages and tells you why they’re slow based on the rules for high performance web sites. YSlow is a Firefox add-on integrated with the popular Firebug web development tool.