Rated 4 out of 5 stars
It was the next best thing to Multizilla. Now it appears that even that is dead, as mattstan hack no longer works (the extension installs but the buttons are gone... :(
All we have left is the redone duplicate tab add-on: https://addons.mozilla.org/en-US/seamonkey/addon/156490/
How I miss the days when I was able to duplicate tabs with their history, close all tabs on the right or left side, reopen closed tabs - not only the last one, but select from the list of all closed tabs, when tabs were colorized based on which other tag they were started from... those were the days. Now, frankly, I am forced to use Chrome - not because I want to, but because at least it has the uber-useful reopen closed tab option... sigh.