It's the hierarchical tabs that I need. If you are traversing large hypertexts you need to keep track of where you are and where you were.

Middle-clicking to open-in-new-tab together with Tree-Style-Tabs is incredibly useful in this scenario.

You can rapidly open a large number of potentially-interesting links in tabs, and then weed out the ones you don't need just as rapidly. Then wash, rinse, repeat. It's an assembly line approach.