Try these commands on the address bar:
about: – shows info on Firefox’s version number, copyright, etc.;
about:config – reveals the Configuration Console, a repository brimming over with scores of customizable settings;
about:cache – displays a summary of both your memory and file cache, with a link to full file listings;
about:buildconfig – lists the compiler options that were used to create your version of Firefox (and, since it’s open source, anyone can compile a customized version);
about:plugins – enumerates your installed add-ons, which can be quite numerous since Firefox is designed to be modular and extensible; and
about:credits – is an “Easter egg” that includes the names of hundreds of developers and testers who worked on the product.
You forgot about:mozilla which is another easter egg that has to be seen to really understand
Don’t forget about:kitchensink, if you have everything, you need that right?
Suppose it wouldn’t have been as interesting to just list about:about and be done with it.