The Firefox Addons homepage can be found here. On this page, I will be reviewing the addons that I have tried.
Adblock Plus: This is a nifty addon that gives you the power to manually banish various flash advertisements from webpages that you frequent. It works on the idea of blocking the URL from which the add is downloaded onto your browser. This is what makes it very powerful, yet highly versatile.
AutoPager: This is an addon that made my browsing much more efficient, especially when I was on forums. This guy works by adding a page break to the bottom of your page and loading the next page right after that break. Essentially, it enables you to scroll to the bottom of the current page and keep scrolling - to the next page of the forum that you are on. Sadly, this doesn't work on the superset of all page'd websites, but it works on enough to be useful. It also eliminates the need to navigate between successive pages of a forum and a "Firefox find command" will span over all the pages that have been loaded so far. This addon also comes with options such as always preloading the first 5 pages of the target page. This is especially useful in forums when you are debating whether or not to go to the next page (hoping that it has your answer) before giving up.
BugMeNot: Bring the power of BugMeNot into one right-click. Simply right-click on the login field of any page and the context menu has the "Login with BugMeNot" option. Clicking this will set the browser to look up the BugMeNot website for any login info and input it, without you having to do it manually. It has failed me less than 5 times in the 100s of times that I've used it, and that's mostly because of improper login credentials supplied bugmenot.com
CoolIris: Primarily for the artsy-fartsies, this visually relaxing addon turns your current tab into a wall of searchable pictures and videos. You can set the number of rows that you would like to see in this wall and there are some impressively smooth scrolling features. Further, it has the capability to play videos on the screen. For those concerned about traffic limits, pictures and videos are only downloaded in Low-Res (first frame of the video is served on the wall). Clicking on them will trigger the full download.
CoolPreviews: The first addon to increase my browsing speed. This adds a small floating icon to the right of any link you mouse-over. Clicking on this icon will load the link in a small movable window with full browser capabilities. Want to make it disappear? Move the mouse off that window. Want to make it not disappear? Click on the "lock" button on the window. The window also lets you bookmark the page that it contains, open it in a new tab/window, etc. Many user options make it very fast and very sleek. Sometimes, however, the floating icon tends to stick at the end of the URL but it's essentially harmless.
Download Statusbar: I hated the additional "downloads" window that firefox always popped up when I was downloading something. This addon turns that window into a statusbar right above the firefox windows's bottom statusbar. Each download shows up as a small bar and the amount of color fill tells you the download status of that download. Mouse-over gives you more inofrmation.
DownloadHelper: Three Cheers for being able to download embedded flash and shockwave files that the author doesn't want you to be able to download. No more needing to go to openflv (or such) to have to download from youtube (or such).
FireFTP: Integrate an FTP client into Firefox. To be honest, I haven't been able to use this fully. I'm not sure if I'm being a noob of if this has a bad UI. But it's not on my badlist yet.
FireGestures: Hooray for not having to reach for the taskbar everytime you want to perform mundane tasks like going back/forward, opening a new window/tab. This addon recognizes gestures and associates them with certain commands. Also, you can make it leave color trails behind your mouse pointer as you perform these gestures.
Fission: Remove the progressbar from the bottom of the firefox window. Integrate it into the addressbar. Now you have an extra line of screenspace on firefox and it looks a little bit like Safari (not that I really care).
Ghostery: What scripts are running on this page? Anything malicious? Anything user trackers? Well this small addon tells all!
Gmail Space: DON'T USE THIS. It turns any Gmail account into a network harddrive. It is awesome at what it does (from what I have seen it do - I personally have not used it). But the big G does not like people using this, especially with the GDrive only heard of in whispers.
Googlepedia: Awesome: integrates the most relevant wikipedia article on a pane to the right of your natural Google search results. Expand/Shrinkable. Bad: Take a while. Freezes your browser if it freezes (not TOO often). Doesn't always find what YOU would consider the most relevant article - FIX: hideable (it doesn't load wikipedia articles when hidden).
Mouseless Browsing: If like me, you love the keyboard and hate the mouse, this addon is for you. It adds a unique number to the end of each link on your current webpage. ctrl-<that number> opens that link. The only downside is that in a page with many links, the number itself becomes long and screws with the dimensions of the page (so sometimes links are moved to successive rows).
Readability: This is not a conventional Firefox addon. But if you read a lot of stuff online, this really helps. It runs some Javascript to turn the page layout to look more like paper and by increasing the contrast make it less of a strain on the eyes and more readable.
Speed Reading Pacer: This is a tool that highlights the words in a webpage sequentially in a pace that you set. All you have to do is highlight the texty that you would like to read and click on their bookmarklet (from their website). This helps you read the page faster and also helps you practice your speed reading in the process.
Status-bar Scientific Calculator: Integrates a light scientific calculator to the Firefox statusbar. perfect for quick calculations. Can be summoned/dismissed by ctrl-<space>.
StumbleUpon: Awesome little tool that lets you browse categorical subspaces of the interweb. It's always brought up interesting webpages for me. Use this one-click addon when you don't know what to do on the web. Awesome surfing tool for finding sites/pages that you never thought existed.
TabRenamizer: One of the most awesome Firefox addons ever. It lets you rename tabs to anything you want for that session. It is especially awesome when you have multiple tabs open that all seem to have the same name scrolling of the tab header.
Tree Style Tab: Another one of the most awesome Firefox addons ever. It puts your tab bar on the left and displays everything like a tree (by indentation). So now you know which (child)tab was opened from which (parent)tab. This non-unilinear tab display is of great help, especially when browsing with multiple tabs on multiple topics
UrlbarExt: A useful, tiny addon that integrates tinyurl, "copy", "search site" etc into the address bar.
Web Developer: Developing webpages for mobile phones etc? Use this to not remember cache/change size/do various other nifty little helpful things. Awesometastic and very light.
Session Manager: It has happened more than once to me that I need to quit firefox and shut down my laptop. But I would like the tabs etc that I have open in firefox now to be available to me when I restart my computer. One way to combat this problem is by hibernating the laptop. But that's not always an optoion (suppose you installed something that requires a reboot). This addon saves the session (tabs windows and all - you can choose) and you can choose to relead the session whenevr you like in the future. It preserves sessions across reboots etc. Quite awesome