I used to be wondering to have enough extensions for myself as supporter of Mozilla Firefox, I totally agree that it built to be more than itself. According to lifehacker.com, they have tried out in the past 2 years and finally come out with the top 10 must-have. I guess this would be helpful and share some opinion with me as well.

No.10 AutoCopy (clipboard helper)

#10: Prevent blisters on your Ctrl+C fingers with AutoCopy, a super-simple extension that does exactly what it promises – transfers text to the clipboard as soon as it’s highlighted. AutoCopy also remembers past clipboard contents items, can append text to the existing clipboard, or open wrapped URLs on a web page in a new tab.
Download AutoCopy >>

No.9 Customized Google (Google enhancer)

#9: What could you possibly want to customize about your favorite Google apps? A whole lot, actually. With CustomizeGoogle installed, you can:
* Remove ads from Google search results
* Add links to results from other search engines
* Anonymize Google’s query tracking cookies
* Remove Gmail’s Spam folder and invite box
* Automatically use Gmail and GCal’s secure connection
* Filter out the sites you never want to see again from Google’s search results
Download CustomizeGoogle >>

No.8 Firebug (Web Development helper)

#8: Probably the geekiest of all 10 picks – and mostly of interest to web monkeys – the Firebug web development extension gives you a peek under the current web page’s hood and gives you the tools to take apart the gears. Browse and edit HTML and CSS markup and watch live previews of your changes as you type. Firebug can help you track down script errors and monitor network usage of page element downloads. (Honorable mention: Chris Pederick’s Web Developer toolbar is also a favorite of mine.)
Download Firebug >>

No.7 FireFTP (FTP client)

#7: FireFTP offers a two-paned interface that lets you browse and transfer files between the remote server and your local computer.
Download FireFTP >>

No.6 GreaseMonkey (Site Specific Script Manager)

#6: Customize the appearance and add enhanced features to the web sites you love with the Greasemonkey Firefox extension, a user script manager that can automatically run custom Javascript on certain web sites. What kind of scripts, you ask? Here are a few examples of what can be done with Greasemonkey:
* Access your Gmail and Google Calendar securely (over SSL) automatically
* Remove excessive !!! exclamation!!!! points!!!!!!!! from web page text, like your teen’s MySpace postings
* Resize textareas to your liking
* Preview full-size images in Google search
* Embed a PLAY button next to music files linked on the web
There are new Greasemonkey user scripts coming out all the time, and with the extension installed, you too can try them out.
Download Greasemonkey >>

No.5 ScrapBook (Web Clipping Library)

#5: Save and annotate bits of text and whole pages from all over the web to your computer with Scrapbook, an amazing web clipping and annotation tool. Create folders of clippings, highlight text inside saved web bits and add sticky note annotations as well.
Download ScrapBook >>

No.4 Tab Mix Plus (Tab Manager)

#4: Tab Mix Plus enhances Firefox’s tab browsing capabilities. It includes such features as duplicating tabs, controlling tab focus, tab clicking options, undo closed tabs and windows, plus much more. It also includes a full-featured session manager with crash recovery that can save and restore combinations of opened tabs and windows.
Download Tab Mix Plus >>

No.3 Download Them All (Download Manager)

#3: Replace Firefox’s lame-o built-in downloads pane with DownThemAll!, an advanced download manager that can speed up your downloads, automatically grab all the images, music or video files on a page, queue, pause and resume downloads too. See more on how to supercharge your Firefox downloads with DownThemAll.
Download DownThemAll! >>

No.2 AdBlock (Advertisement Blocker)

#2: Are we an ad-supported web site? Yes.
Do we want you to block our ads? No.
Are there SOME web sites that hit you over the head with talking banners and flyover ads that deserve to be blocked? YES!
That’s where Adblock comes in. If Adblock worked in real life, Times Square would be filled with blank, white buildings. Save yourself from a seizure and quiet down those talking, blinking ads that distract and take away from the good stuff on the web. With Adblock, you can block images, iframes, flash movies and other adverts on a URL basis (with wildcards capability) that you can configure. Just please don’t tell our advertising department you heard about it from us.
Download Adblock >>

No.1 Foxmarks (Bookmarks Synchronizer)

#1: Never lose your bookmarks when you move to a new computer again! The Foxmarks bookmark synchronizer keeps your bookmark lists in sync across multiple computers, even if you’re using Firefox on more than one at the same time. Foxmarks makes a copy of your bookmarks to its servers – or your own server – so if your copy of Firefox crashes or you move computers, you’ve still got easy access to your master bookmark list. (Honorable mention: Google Sync, for syncing passwords and tab sessions as well. Still, we like Foxmarks better.)
Download Foxmarks >>

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