I stumbled across a great Firefox add-on/extension (whatever they are called these days!) .. it’s called Tree Style Tab. It shows the tabs in a tree down the left or right hand side, incredibly useful when you have loads of tabs open, it really helps to see which tabs are related and how you got to your current tab. A few nice options too, checkout the auto hide option with it’s transparent background and when the panel hides it doesn’t have to hide completely, it can just be smaller! cool.