PasswordMaker looks like a decent security add-on for Firefox. But there could be at least a couple of considerable gotchas.
The tool lets you store all your passwords for all the protected sites you access. It can also generate random passwords for you that are allegedly hard to crack. PasswordMaker uses several variables to generate a random password. It then stores the passwords in a hashed format using any of 10 different hash algorithms. In order to use a given password you must only remember the master password. So in effect PasswordMaker simplies remembering passwords since all you need to remember is one password.
This leads to me the gotchas. If for whatever reason you forget the master password then you're out of luck and won't be able to recover any of the stored passwords. The second gotcha has to do with the nature of Firefox itself. Since PasswordMaker is an extension it relies on version numbers for Firefox. As you might know, when you load a new version of Firefox any extension that doesn't work with the current version is automatically disabled and therefore you can't use it. So hopefully you remember to check for compatibility issues with PasswordMaker before you upgrade to a new version of Firefox, otherwise you'll be locked out of all the sites that require you to enter your password.
Granted, extension writers get to specify which version of Firefox an extension works with so you could edit the extension files to possibly get an extension working again with a new version of Firefox. I've done this before on many occassions and sometimes it works, sometimes it doesn't. It depends on the extension itself and whether changes to Firefox have any impact on functionality. Either way, editing extensions is a lot of trouble to go through.
There is a PasswordMaker FAQ that answers a lot of questions too