It good, just not what I want - it takes up too much screen space. If it could be made narrower to the point where only favicons were displayed....

On a side note - to hide the tab bar Firefox stuck up top, add the following to your (user profile)/.mozilla/firefox/chrome/userChrome.css file:

/* Hide the tab bar */
#tabbrowser-tabs { visibility: collapse !important; }


If you want to move the tab bar below the toolbar add:

/* Tab bar below Navigation & Bookmarks Toolbars
For best results, show Title Bar or Menu Bar */
#nav-bar { /* main toolbar */
-moz-box-ordinal-group: 1 !important;
border-top-width: 0 !important;
}
#PersonalToolbar { /* bookmarks toolbar */
-moz-box-ordinal-group: 2 !important;
}
#TabsToolbar { /* tab bar */
-moz-box-ordinal-group: 3 !important;

Looking forward to a version that's more compact (or ideally moves tabs to bottom of screen).