1. Download Statusbar was one of the first add-ons I ever really liked. Instead of dealing with a separate ‘Downloads’ window when you download something, it makes use of the bottom of your window, like a status bar, to show the progress of your download. This is way more convenient and very much the same way Google Chrome handles downloads.
2. Adblock Plus blocks the vast majority of popups and banner ads, including ones that utilize flash or scripts as well. It also comes with a list of known ad suppliers to block that is automatically updated so you don’t have to do anything. This overall speeds up load times and removes distractions. Only when I go on someone else’s computer do I notice all the ads I’ve been missing out on. Highly recommended!
3. TinEye is a reverse image search engine I use often when I find an image I like and want to find the higher resolution of it. I can go to www.tineye.com to do this but with the add-on installed, all I need to do is right click on any image and click “Search image on TinEye” and it’ll pop up the results in a new tab automatically.
4. Imgur Uploader allows you to easily upload images on the web and screenshots of webpages (or parts of web pages) straight to Imgur using a simple right click menu. Lightning fast!
Hope that helps!