Firefox only (Windows/Mac/Linux): Firefox extension Tree Style Tab adds folder-tree-like navigation to your tab management, organizing tabs based on the order in which they were opened and the pages they originated from. The main idea behind Tree Style Tab is that you can keep track of the relations of your open tabs to each other so you can always follow the breadcrumb trail back to where you started—especially handy when you’re researching something and end up with an endless pile of unorganized tabs. The extension’s options are highly configurable, allowing you to customize the tab bar location, behavior of new tabs, and more. Tree Style Tab is free, works wherever Firefox does (including Firefox 3 betas).
Sanket Sonavane Senior Developer, IoT Enthusiast, Photographer, Bike Rider, Chef, AndroidUser, MacOSX Fanatic ;) Loves computers, programming, web developement, micro-controllers, gadgets, automation and many more such tech innovations that defines the way we live in the modern age and likes to explore what more can be done to help the human race :)