Add-ons that I am trying out and haven't yet developed my opinion upon.
An extension that adds direct links to download YouTube videos as MP4 and FLV. It has a simple interface and it downloads videos directly from YouTube. The extension integrates with YouTube's interface and adds a download button below the player.
The simplest YouTube Video Downloader for all YouTube Flash sites, period.
Download Flash and Video is a great download helper tool that lets you download Flash games and Flash videos (YouTube, Facebook, Dailymotion, Google Videos and more) with a single click.
The downloader is very easy to use.
Use PDF Download to do whatever you like with PDF files on the Web. Regain control and eliminate browser problems, view PDFs directly in Firefox as HTML, and use the all-new Web-to-PDF toolbar to save and share Web pages as high-quality PDF files.
Make any pages' search functionality available in the Search Bar (or "search box")...
The official extension from the people at Dictionary.com, the most popular and trusted online dictionary and thesaurus, to look up word definitions and synonyms anywhere you go with Firefox via a simple pop-up.
Dead pages, broken links, the scourge of the internet. Powerhouse sites like Slashdot and Digg can bring a server to its knees. What do we do when a page is dead but we still want to see it? Call in the clerics, and perform a resurrection...
Easily share web pages you like with your friends and see how many people on Facebook like the page you are on!
Get a FREE tool to write without mistakes on Facebook, Gmail, Twitter, Tumblr,
Linkedin, and anywhere else on the Web.
★ Contextual spell checker
★ Grammar check
★ Punctuation correction
Autosizes the searchbar as you type, cleans the query or reverts to your default search engine after submitting. Supports almost all themes and various search bar related extensions. Useful for saving space on a small screen.
Change location of Status Bar Icons, Firefox Menu Button and Menu Bar and more.
LinkExtend provides meta-site-ratings for computer safety, child safety, company ethics, and popularity. Safety results come from eight online services giving you a safer browsing experience. Site links, titles, files and reviews are also included.
Button changes state to Notify you about:☎ Facebook Notification✉ New Facebook Message Alert☛ Facebook Friend RequestAlso Includes a 1 click Facebook Like Button.Available as standalone browser buttons or as part of the MediaPimp toolbar.
QRCode (2D barcode) generator extension for quick data-to-smartphone transfer! Supports links, images & text selection codes.