Whenever I have to prepare a new Firefox installation, I tend to forget at least one of my all time favorite Firefox add-ons.
As a reference, I compiled a small list of my basic setup. You might find it useful:
* Adblock Plus
Ever been annoyed by all those ads and banners on the internet that often take longer to download than everything else on the page? Install Adblock Plus now and get rid of them.
* FireGestures
A customizable mouse gestures extension which enables you to execute various commands and user scripts with five types of gestures..
* It's all Text
Edit textareas using an external editor, because it's all text!
Right click on a textarea, select "It's All Text!" and edit the text in the editor of your choice.
Alternatively, click on the edit buttons added for your convenience. Right click on the edit buttons for even more options, including preferences.
* Google Reader Watcher
Checks your Google Reader for unread news
* Shareaholic
Found something awesome online and can’t wait to pass it on? Tired of copying and pasting endless URLs? Shareaholic allows you to share, bookmark and e-mail web pages quickly without leaving your browser.
* Firebug (currently beta for Firefox 3)
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.