Let’s say you have a lot of tabs opened. Some are from one site, several others are from another site and they’re all mixed. It can be pretty confusing finding the right tab. Fortunately, that won’t be a problem anymore. With this extension, called Separate Tabs, Firefox automatically separates tabs from one site into a group and tabs from other sites into another group, placing a separator between the groups. It’s much easier browsing through tabs now that you know which site every tab belongs to. Try it yourself! Download Separate tabs here.
Source: BARRY’S BEST BLOG