Sidebery - Manage your tabs and bookmarks in sidebar.
Lightbeam for Firefox - Mozilla is the not-for-profit behind the lightning fast Firefox browser. We put people over profit to give everyone more power online.
Tree Style Tab - Tree Style Tab is an all-in-one Firefox extension that provides ability in order to operate tabs as a tree.
island - a free and opensource alternative to parellel space
Tab Workspaces - Organize your tabs into workspaces.
App Cloner - Clone your Android apps so you can use multiple logins.