Anti Phishing idea

Interesting talk by Simpson Garfinkel at the CRN/CFP conference on Key Continuity Management (KCM) as a way of improving security over no security. He mentioned the idea of the browser keeping a log of number of times you have visited a website. So if you went to a phishing site it would warn you - First time you have visited this site - and would build a log that you could edit and control.
What a great idea for a Firefox extension? Anyone out there that can do it?

Could also generate a popularity index that could be aggregated like Technorati....