Tree Style Tab - Tree Style Tab is an all-in-one Firefox extension that provides ability in order to operate tabs as a tree.
TreeCard - The wooden debit card that plants tree powered by Ecosia
Simple Tab Groups - Create, modify and quick change tab groups. Features:
TreeMapper - TreeMapper is an easy-to-use tool for standardized on-site data collection on forest restoration.
Sidebery - Manage your tabs and bookmarks in sidebar.
Treeapp - Plant a tree for free, every day, in less than a minute