Tree Style Tab [1]. That is the main reason I am on Firefox. My screen is wider than it is tall, so I can make use of this by displaying the tabs on the side. It is 'tree style' which means that it is nested. This allows me to have child tabs of say, hn for reading all of the different articles. This can be easily collapsed, expanded or removed altogether.

1. https://addons.mozilla.org/en-US/firefox/addon/tree-style-ta...