Ok, this is not exactly targetted for web developers but it is always the first extension I download everytime I need to install Firefox. Tab browsing is great, but it is even greater with Tabbrowser extensions. You can fine-tune how the tabs behave for different type of links, show them on the side rather than on top, automatically open new links in new tabs, group tabs, and so on. But the single feature that I can't live without is tab ordering. You can click and drag tabs to re-order them. If you are like me who often have 10 or more tabs open, this feature is a God-send.

Fig 13. Tabbrowser Extensions options

So there you are, my reviews of some of the most useful Firefox extensions for web developers. As the numbers of extensions keep growing, I'm sure that there will be others and I will add more reviews in the future.