Firefox 3 added a much improved location bar which searches your URL history, bookmarks, tags, etc while you type. For power users wanting to control/tweak the behavior of the location bar, check out this article titled ‘Firefox 3.5 Location Bar Preferences‘.

The author gives you a detailed explanation of exactly how the location bar behaves as well as how to manipulate it. The topics covered are:

1. Toggle suggestions on and off
2. Customize what results get shown
3. Change the matching behavior as you type

Note: I would only recommend those who know what they are doing tweak these settings, otherwise you may end up hosing your Firefox configuration data.