Tree Style Tab is a Firefox addon that provides tree-style tab bar, like a folder tree of Windows Explorer. New tabs opened from links (or etc.) are automatically attached to the current tab. If you often use many many tabs, it will help your web browsing because you can understand relations of tabs.You can also set it so that when closing a 'parent' tab, all attached tabs are also closed (this is very handy if say: you search something on google and open a few search results. Then, when closing the parent tab: Google, all it's sub-tabs are also closed), also you can set it to auto-hide and change it's width to whatever you want (for instance you can set it so you only see the favicons on tabs), put it on the left or right side of Firefox and many (i mean really: a lot!) other options to customize the way tabs are displayed.
There are also some themes for the way tabs look.
This addon works well with most Firefox tab addons such as Tabmix Plus. You may also want to check out this short video to see it in action:
Tree Style Tab [via labnol]
