sorted by perceived usefulness

Adblock

no-brainer

no-brainer Webdeveloper

easy access to a lot of useful things like CSS, validation etc.

easy access to a lot of useful things like CSS, validation etc. Cookiebutton

very easy way to lookup and change cookie permissions

very easy way to lookup and change cookie permissions Colorful Tabs

makes it easier to keep track of multiple tabs

makes it easier to keep track of multiple tabs Firebug

integrated DOM Inspector and Javascript Console

integrated DOM Inspector and Javascript Console Selenium IDE

record macros in Firefox, not working 100%

Did I forget anything essential?

Update:

Thanks, yes I did forget Live Http Headers. Form History Manager seems useful, too.

I forgot All Customized Links, too. This extension allows you to add custom links to the context menu. I use it for some bookmarklets so I don’t have to move to the top of the browser all the time to click them…

Technorati Tags: firefox extensions