Sidebery - Manage your tabs and bookmarks in sidebar.
Tabs Outliner - Next Generation Session, Windows, Tabs Manager and a TooManyTabs Solution That Really Works.
Tree Style Tab - Tree Style Tab is an all-in-one Firefox extension that provides ability in order to operate tabs as a tree.
Tab Utilities - Tab Utilities is an ultimate tab solution for all kind of users who want to manage their tab, create multiple session and search for new tabs, etc.
Firefox Multi-account Containers - Sign in to two different accounts on the same site
Undo Close Tab - Reopens the last closed tab.