Rated 5 out of 5 stars
Works great after tweaking the following undocumented setting from defaults/preferences/listalltabsmenu.js in about:config
extensions.listalltabsmenu.disable.undoclosetab = true
Edit: this option is documented under "Version Information" for 2.4
This preserves the Firefox 4+ middle-click on tab-bar to open a new tab, instead of opening the last closed tab like version 2.4 of this extension.
This extension lets you close/manipulate tabs by middle-/right-clicking on them from the "all tabs" list. I can't believe that this isn't built into Firefox! (Normal behavior ignores middle-click, and right-click brings up Customize; admittedly, right-click *used* to work in Firefox 3.6)