Mozilla Firefox is one for the browsers that is used quite a lot and though it is not a pioneering web browser to support extensions but is has one of the biggest library of them. Independent developers have been creating Firefox adds on that are customized, plus there is library with many choices, it is really tough to pinpoint which are the best. However here is a list that will help your browser do even better.
Greasemonkey: The ultimate in all extensions this one can run many user created scripts and can tune the internet in many ways.
Ghostery: Many may not know this but browsing rarely remains private as most sites have trackers and bugs that gather data on what you look at. Ghostery will keep away more than 1000 bugs and also tells you about the ones that are being blocked
AutoPager: This one will do away with the need to click next page for all time.
FasterFox: This one will make Firefox work quicker
TinEye reverse image search: This will help you track images in different formats and sizes.
Lazarus: It will help in recovering things that you put into form fields.
gTranslate: This one will translate any text that you want translated by merely highlighting and right clicking text
Lastpass: This one will help save your passwords with utter safety and also help you create secure passwords for any new accounts that are created
HTTPS Everywhere: It ensures that your communications with major sites making in https instead of https to ensure secure browsing.
TrackMeNot: This one ensures that your browsing habits remain private by transmitting haphazard queries once in a while
Better Privacy: This one will let you manage locally shared objects
WOT: This one will tell you about the security level of a link prior to clicking on it
FEBE backup: This one will backup all your add-ons and saves them on your computer
Invisible Hand: This extension that will help you in shopping by listing many sites for shopping and help you find the best rates for things you are shopping for.
Thumbnail Zoom: This one will let you view thumbnails properly by just mousing over it.
Image Preview: This one is good for zooming but works for image links and provides you a preview by merely hovering over the link
Image Zoom: This one will make images bigger as you linger over then with the mouse
YSlow: This one will keep you updated when the page you are visiting is slow
Site to Phone: It will transmit what you are seeking on the computer to your mobile
Adblock Plus: Helps keep out those pesky advertisements on the net
WindowShopper: You can have a great online shopping experience as this makes it more visual.
All-in-One Gestures: Will let you carry out many commands with rocker navigation, page scrolling, mouse gestures and scroll wheel navigation
Omnibar: You can have the functionality of Chrome Omnibar right on Firefox.
Copy Plain Text: You can use this to copy text without the formatting
CryptoCat: It is a secure client for chatting to ensure that all messages are safeguarded
Pocket: This extension is great if you find that you don’t have enough time to read a complete article online
ClipConverter: This one will download a video very quickly, easily and in a versatile manner