Did you know that typing “about:” plus another word in Firefox will allow you to view special configuration information of the browserâ€”some of which you can actually tweak and customize?
To try it, type “about:” to show general and version information. Try “about:cache” to view the browser cache, or “about:plugins” to show plugin information. If you are feeling adventurous, try “about:config” to show the browser configuration settings (but be careful when changing settings here). And for some extra fun, type “about:Mozilla” to see a special things provided by the developers.