Here's a list of FIrefox extensions that I've found very useful.
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.
Make any pages' search functionality available in the Search Bar (or "search box")
Note, its even more useful, if you give each search engine a keyword, because then you can search directly in the location bar.
Never be annoyed by a Flash animation again! Blocks Flash so it won't get in your way, but if you want to see it, just click on.
Note. In combination with Ad Block Plus, the web becomes so much nicer to use.
Note. Only for real computer geeks.
Allows hiding of almost anything via context menu 'Remove Object'.
Note. Can be particularly useful for those people who like to print out web pages, but don't want to waste ink printing out irrelevant stuff, such as navigation, adverts, legal notices etc.
Paragrasp is an absolute necessity for anyone who frequently reads blogs, articles, and news stories online. This Firefox extension adds a highlight to the paragraph you're reading, and with a single keystroke, moves to the next, automatically.
Direct access to your most visited websites.
Note. I think they borrowed this idea from "Opera", a closed source, but very inovative web browser.
One use of Tark to harvest bookmarks that are of interest now but may not be in a few weeks.
Show tabs like a tree.
Note. This is useful for those unfortunate to have a wide screen monitor. Why? Because it puts the tabs in a column on the left, instead or in a row along the top. This frees up some of the valuable height, while using up some of the over abundant width.
Note. There are lots of plugins that do a similar thing, and I haven't checked which is best. If you find a better implementation, please tell me.
Adds a menu and a toolbar with various web developer tools.
Note. This is a huge extension, packed with wonderful features. Highly recommended for all web developers.