OK, here ya go:
NoScript:
https://addons.mozilla.org/firefox/722/Extra protection for your Firefox: NoScript allows JavaScript, Java and other executable content only for trusted domains of your choice, e.g. your home-banking web site. This whitelist based preemptive blocking approach prevents exploitation of security vulnerabilities (known and even unknown!) with no loss of functionality...
Tab X:
https://addons.mozilla.org/firefox/785/Adds a close button to each of the browser tabs, and removes the close button at the end of the tab bar.
TinyUrl Creator:
https://addons.mozilla.org/firefox/126/TinyUrl brings the
http://tinyurl.com functionality into your browser. It takes a long URL as input, and gives you a short URL to use in it's place. VERY useful for Yahoo Groups where the URL may span 3-4 lines and won't work unless it's cut/pasted into the browser address.
BBCode:
https://addons.mozilla.org/firefox/128/Adds BBCode/HTML/XHTML formating to the context menu for forums.
Adblock Plus:
https://addons.mozilla.org/firefox/1865/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. Right-click on a banner and choose "Adblock" from the context menu - the banner won't be downloaded again. Or click Adblock Plus icon in the toolbar to see all elements of the page and block the banners. You can use filters with wildcards or even regular expressions to block complete banner factories.
Adblock Filterset.G Updater:
https://addons.mozilla.org/firefox/1136/This is a companion extension to Adblock or Adblock Plus and should be used in conjunction with it. This extension automatically downloads the latest version of Filterset.G every 4-7 days. Filterset.G is an excellent set of filters maintained by G for Adblock that blocks most ads on the internet. In addition, this extension allows you to define your own set of filters that you can add along with Filterset.G during an update. (Since the recent update to FF, this is currently inop, but should be updated soon.)
eBay Negs:
http://members.aol.com/caymanisle/Displays all the Negative Feedback an eBay user has received via right-click or Tools menu.
SessionSaver:
https://addons.mozilla.org/firefox/436/SessionSaver restores your browser -exactly- as you left it, every startup, every time. Not even a crash will phase it. Windows, tabs, even things you were typing -- they're all saved. Use the menu to add + remove sessions; right, shift, or middle-clicking will delete. "Simple mode" for peace of mind, or "Expert mode" for advanced flexibility. Just Click. Install.
DictionarySearch:
https://addons.mozilla.org/firefox/68/Looks up a user selected word in an online dictionary
del.icio.us:
https://addons.mozilla.org/firefox/2354/del.icio.us is a social bookmarks manager. It allows you to easily add sites you like to your personal collection of links, to categorize those sites with keywords, and to share your collection not only between your own browsers and machines, but also with others.
I saved one of the best for last...
Smiley Xtra:
https://addons.mozilla.org/firefox/375/Insert smilies from an online database into forum posts, blogs and more!