I like that "Vertigo Tabs" provides a display of "open Tabs" in the current Firefox window, (the display appears on left side of screen and I can narrow/widen its display field). While I must close the tab at top of screen (a minus), the ability to display ALL open tabs in the current window (even though only perhaps 40 will actually display at a time), helps greatly in knowing what all I've kept open in tabs, (though perhaps it also encourages me in the bad habit of opening TOO MANY tabs). All in all, I consider this, to be one of my MOST valuable Add-Ons.