Must have firefox & Chrome extensions for Web developers and designers
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.
Colorzilla
Advanced Eyedropper, ColorPicker, Gradient Generator and other colorful goodies.
MeasureIt On
Draw a ruler across any webpage to check the width, height, or alignment of page elements in pixels.
LightShot
Easy and convenient screenshot tool. Allows you to make screenshots of any selected area (video and flash too), edit and upload it to server.
https://addons.mozilla.org/en-US/firefox/addon/lightshot/
Now also avialable for Windows and Mac
http://app.prntscr.com/
IE Tab 2
IE Tab for Chrome (and IE Tab 2 for Firefox) is a browser extension that allows you to use Internet Explorer to display web pages in a tab. This is useful in many cases where a web page requires Internet Explorer features.
http://www.ietab.net
Abduction! – Webpage Screenshots Screen Capture
1) Capture an page or just a specific region.
2) Adds a right click option to take screen shots of an entire web page or just part of a web page to save as an image.
https://addons.mozilla.org/en-US/firefox/addon/abduction/?src=api
Updated : 4/24/2014
