ComputerWorld takes a look at some hidden Firefox tricks:
Ever since its debut, Firefox has garnered a reputation for being an enormously customizable program, both through its add-on architecture and its internal settings. In fact, many of Firefox's settings aren't exposed through the Tools > Options menu; the only way to change them is to edit them manually. In this article, we'll explore some of the most useful Firefox settings that you can change on your own, and that aren't normally available through the program's graphical interface.
The closest analogy to how Firefox manages its internal settings is the Windows Registry..