The Web of Trust comapany recently released a 'Surf Safer and Smarter' firefox addon collection featuring:
Web of Trust
I use Adblock Plus and Web of Trust so I definitely recommend those to keep yourself safe. I don't recommend Robofor Toolbar because the free version is limited to remembering only 10 logins. Firefox already has a built in password manager system and there are other free ad-ons without the 10 login limit. I use Secure Login myself.