Finding out passwords saved in firefox is as easy as tools>options>privacy>passwords>view saved passwords>show passwords, and voila a complete list of usernames and passwords with the site they belong to, I do tell firefox to save my non-vital passwords, however i also set a master password for the saved passwords, this is a great little feature what it means is everytime when you first start firefox, before it will show any passwords using the method above, or enter any passwords into a site for you it asks you for a password which you just enter once until you close firefox down and start it again. I don't know if this hashes/encrypts your password list though. If you want to do this go to tools>options>privacy>passwords>set master password