I remarked before that the proposed Ctrl-Tab behavior for Firefox 3.1 is a UI disaster. Here’s a different proposal from Aza Raskin. Rather a different and much more interesting idea who’s time has come: using the address bar to take you straight to your destination, be it a new page or an already open tab.
Personally, following Hick’s law, I’d like to see the address bar as the first step into any destination you can name, including bookmarks, configuration panels, and most menu actions. Modal interfaces are so IE 6.