Passpet is a Firefox extension that makes passwords stronger and easier to use and protects you from phishing attacks.
When you use Passpet, you only have to memorize one password. You can fill in login forms just with one click on Passpet.
Every site you use gets a different password, so a break-in at one site won't expose any of your other accounts. The calculation of the site-specific passwords is designed to make it hard for an attacker to break in by trying to guess your password.