Does your online banking or company intranet never remember your username and password? If you save your passwords in Firefox but still have to type 'em in by hand on certain sites, they probably disable login credential autocomplete. The How-To Geek says that the right Greasemonkey user script can re-enable that handy functionality on some sites. (Sadly it didn't on my bank's login page, but on others it will.) If a site disables password-saving, it's probably doing that for good reason, so use this tip at your own risk. And remember: if you are saving passwords in Firefox, lock 'em down with a single master password .
Why Doesn't AutoComplete Always Work in Firefox? [The How-To Geek]