There are thousands of add-ons but for better results you must have these Add-ons.I selected these add-ons as important for firefox users.
1. FlashGot
Download one link, selected links or all the links of a page together at the maximum speed with a single click, using the most popular, lightweight and reliable external download managers. The new "FlashGot Media" command grabs video and audio clips while they're playing, too. Supported download tools are dozens, see http://flashgot.net for details.
Download FlashGot
2. Read it later
Download Read it later
2. Read it later
Save pages to read later with just one click. When you have time,
access your reading list from any computer or phone, even without an
internet connection.
Download Read it later
3. Easy YouTube Video Downloader
Easy YouTube Video Downloader is the fastest YouTube downloader add-on available online! Download YouTube videos as 128kb MP3s up to 30x faster than any of the competing downloaders. We offer the highest sound quality available and our free YouTube downloader works directly within page! Download and convert YouTube videos as high quality M4A, AAC, MP3, MP4, FLV, and MPEG files. With Best Video Downloader, it's never been easier to download from YouTube!
4. BetterPrivacy
Better Privacy serves to protect against special longterm
cookies, a new generation of 'Super-Cookie', which silently conquered the Internet. This new cookie generation offers unlimited user tracking to industry and market research. Concerning privacy Flash-cookies are most critical.This add-on was made to make users aware of those hidden, never expiring objects and to offer an easier way to view and to manage them - since browsers are unable to do that for you.Download Better Privacy
5.Xmarks Sync
Xmarks is the #1 bookmarking add-on. It takes only a moment to get up and running with Xmarks. After you install the add-on, click on the notification to set up Xmarks and start backing up and synchronizing your bookmarks. Install Xmarks on each computer you use, and it seamlessly integrates with your web browser and keeps your bookmarks safely backed up and in sync.
6. WOT - Safe Surfing
WOT is the leading website reputation rating tool and one of Mozilla’s most popular add-ons. WOT uses a traffic-light rating system to show you which websites you can trust when you search, surf and shop online.
WOT ratings are powered by a global community of millions of users who rate millions of websites based on their experiences. You will see green, yellow or red icons next to search results on Google and Yahoo, links on social networking sites Facebook and Twitter, web based email such as Gmail and Hotmail, Wikipedia, and many other popular sites.
WOT ratings are powered by a global community of millions of users who rate millions of websites based on their experiences. You will see green, yellow or red icons next to search results on Google and Yahoo, links on social networking sites Facebook and Twitter, web based email such as Gmail and Hotmail, Wikipedia, and many other popular sites.
7. Facebook Toolbar
Search Facebook from anywhere
Get Notified
Icons on the toolbar tell you how many new pokes, friend requests, and messages you have. A pop-up will notify you when your friends update their statuses, write a new note or interact with you on Facebook.
Connect with Friends
Click the icon to open the Facebook friends sidebar. You can sort your friends by name or status and easily interact with them and their profiles.
Share Content
The share button lets you share the page that you are currently browsing by sending it to friends or posting it to your profile.
Upload Photos
The upload photos button lets you find photos on your computer, caption and tag them, and upload them to Facebook.
Icons on the toolbar tell you how many new pokes, friend requests, and messages you have. A pop-up will notify you when your friends update their statuses, write a new note or interact with you on Facebook.
Connect with Friends
Click the icon to open the Facebook friends sidebar. You can sort your friends by name or status and easily interact with them and their profiles.
Share Content
The share button lets you share the page that you are currently browsing by sending it to friends or posting it to your profile.
Upload Photos
The upload photos button lets you find photos on your computer, caption and tag them, and upload them to Facebook.
8. Speed Dial
Direct access to your most visited websites
9. FireFTP
Along with transferring your files quickly and efficiently, FireFTP also includes more advanced features such as: directory comparison, syncing directories while navigating, SFTP, SSL encryption, search/filtering, integrity checks, remote editing, drag & drop, file hashing, and much more!
10. Integrated Gmail
Allows you to make the Inbox Collapsible and loads your choice of Google Calendar, Reader, Tasks, Wave, Notebook, Groups, Maps, Picasa, Sites, News and Portfolio plus Custom URLs (w/navigation buttons in frame) and Google Gadgets seamlessly into the Gmail interface below the inbox (rather than the sidebar) using a collapsible box. If your are inbox minimalist, enable minimalist mode to clean up the inbox even more.