I avoid browser tabs if possible. I currently have 5 browser windows open, and have hacked userChrome.css to hide the tab bar:

  #pageActionButton {
    display: none !important;
  }
  .urlbar-history-dropmarker, .urlbar-history-dropmarker:hover   {
    display: none !important;
  }
  #TabsToolbar { visibility: collapse; }

I currently have 12 visible windows open. I prefer a spacial interface where I can see and change everything vs. a modal interface of only seeing one task at a time and having to constantly switch between each task/tab.