Google has released a Firefox extension called Google Safe Browsing which help to identify false web sites (known as phishing or spoofing), to protect your personal and financial information. With serveral technologies including user backlist reports and other algorithms, it alerts you whenever the site is flagged as a web forgery. Here is the introduction from the site:
Google Safe Browsing is an extension to Firefox that alerts you if a web page that you visit appears to be asking for your personal or financial information under false pretences. This type of attack, known as phishing or spoofing, is becoming more sophisticated, widespread and dangerous. That’s why it’s important to browse safely with Google Safe Browsing. By combining advanced algorithms with reports about misleading pages from a number of sources, Safe Browsing is often able to automatically warn you when you encounter a page that’s trying to trick you into disclosing personal information.
Download Google Safe Browsing for Firefox – [Google]