Have you ever tried these hidden commands in the address bar of your Firefox.If not,then try it..
about:
A simple prompt without any parameter will display the Mozilla “about”
information. Since it’s accessible from the top menus as well, it’s not
quite a hidden feature.
about:buildconfig Obviously, it will show the build platform configuration and parameters
about:cache
Will display info and statistics regarding your disk’s cache, including
the name of your cache’s directory and a list of the entries you can
find there. By default, Firefox doesn’t allow you to view the cached
webpages, so this can be an useful option.
about:config
Oh look, many many info. Indeed, it’s the most complex and meaningful
of them all. Careful on what you plan to change here, your browser
won’t run properly after if you play with the wrong things.
about:plugins
Of course, what is Firefox without it’s powerful extensions? This
option will display detailed information about all the plugins
installed for Mozilla Firefox.
about:credits
It’s time to give the credit to whoever deserves it. There’s an
alphabetically sorted list of all the people that gave their
contribution to the development of Firefox.
about:Mozilla
This is a weird thing. It will display the so-called “Book of Mozilla”.
Something similar was present in Netscape too. There’s actually no real
book although the quotations might give you that impression.
If you have other similar tricks then don't hesitate to comment here.