Separe - Mozilla add-on that helps you keeping tabs tidy by introducing a new kind of tab!
Version: 0.1.6If you get used to tabbed browsing, you can find yourself with a large amount of tabs. With Firefox you can reorder them by drag and drop, but when you have many tabs it's difficult to recognize them, since their width shrink as they grow in number. Furthermore the default behaviour when opening a new tab or a link in a new tab is to append it to the list of tabs.
Operating System: Mac OS X
If you are browsing different web pages and you open some links inside them alternatively, you end up with a messy sequence of tabs.