This Firefox add-on arranges tabs in a vertical rather than horizontal fashion.
Hide and display manually the tab sidebar with a hotkey (Ctrl+Shift+V) or by clicking on the VTR icon.
Vertical Tabs Reloaded is a fork of Vertical Tabs , inspire.
Kurator Alternatives
Kurator is described as 'Lets you curate links into special folders, that you can pin to your browser tabs. The program scrapes information off the page and lets you add and modify description, author, publisher and content tags. Instant access to your info!' and is an website in the office & productivity category. There are more than 25 alternatives to Kurator, not only websites but also apps for a variety of platforms, including Mac, Google Chrome, Windows, Linux and Mozilla Firefox apps. The best Kurator alternative is OneTab, which is free. Other great sites and apps similar to Kurator are Session Buddy, Tab Stash, Sessionic and Tabs Outliner.