In this screen shot you can see the title for this site displayed in Firefox. As you can see Firefox places the title at the top of the page, as well as a truncated version in the tab and in the bookmarks. Firefox uses the title here:
- The browser window
- The tab truncates the title
- The bookmarks
- The auto-complete drop-down when typing a URL
I couldn't get a screen shot of Firefox with the auto-complete drop-down open, so try that for yourself. It auto-completes with the title on pages you've bookmarked and pages that it's been to before.