In most browsers, the URL value can often be auto-completed, either by looking up similar URLs from the history or by using keyboard shortcut for URL completion. For websites which use favicon (a small icon that represents the website), there will also be a small icon in the URL bar.
The URL bar is also used, in some web browsers, to indicate the security status of the web page. Various colors and padlock icons show if the page is encrypted and how trustworthy the communication is. In Safari (and, optionally, in Opera), the URL bar also doubles as a progress bar that indicates how much of the content of the page has been loaded. It can also be used to detect RSS feeds that can be used to subscribe to pages.