This is bar none the coolest extension to come out for Firefox since AdBlock. It blocks all types of scripts from running on any site until you whitelist the site. The status of blocked content and controls are easily accessible from a panel at the bottom of the browser. Whitelists can be imported/exported (for backup/restore or faster whitelist generation) from text files en masse.
Check out the Mozilla Extension page or the official site.
Something that seems to be an enormous pain for most people, me included, is Adobe's wonderful idea of loading Acrobat documents within web browsers on Windows PCs. Enough people seem to think this is a great idea that much effort has gone into making it work.
While such an item may be fine and dandy on Apple's systems, where Acrobat PDF is the native file format, I can safely say that on every one of my many PCs and OS installations I have ever used, the Acrobat browser plugins have always caused me much suffering, locking up my browser and/or Acrobat's independent window and forcing me to kill either or both processes.
While examining the Firefox GoogleDrupal search plug-in, I noted the simplicity of the Mozilla search plug-in source and saw why it is that there are so many search plugins available for Firefox/Mozilla. (Check for yourself, click the search field drop-down arrow on the icon and then click Add Engines...)
Everything you need to know about Firefox:
My recommended list of what you should get:
Also, be sure to check out my other articles on both Mozilla (Firefox) and Google.
One thing about Firefox is that though it might be more simple, and therefore more user-friendly, than Mozilla, it certainly has far fewer configuration options. There are extensions for Firefox which can give the user a portion of that control back that was removed from the user interface, in fact there is a whole category at the Extension Room that is dedicated to tweakers. Also, there are always the options of manually editing the configuration files, but I've just stumbled across a forum clue that opened my eyes to something so much nicer and immediately accessible in any Mozilla browser. Simply type about:config in the URL field and hit ENTER.