Organise you tabs in a Tree, this add-on for Firefox provides tree-style tab bar, like a folder tree of Windows Explorer, useful for anyone who has numerous tabs open at once. New tabs opened from links (or etc.) are automatically attached to the current tab, it will help your web browsing because you group tabs together. Features:

• You can collapse/expand sub trees.
• When you close a tab, all of tabs in the sub tree will be closed
• Vertical tab bar can be shown/hidden automatically.
• You can open new tab between existing tabs.
• You can save/restore the tree of tabs over sessions
• Drag and drop is available to modify order of tabs and to rearrange.
• Tab bar can be moved to any position. Supports
• Firefox: 2.0 – 3.6a1pre