A really well-known old attack, far more painfully expressed in internationalized domain names (IDN), where attackers can create pixel-perfect DNS clones of "paypal.com".

Notable also as an example of an attack that the DNSSEC security model does little to combat.

One of the biggest security weaknesses on the Internet is in browser UI (something Aza Raskin should be shouting from the rooftops). Right now, users are "trained" (to dignify what's happening) to look at the browser URL bar for a name and a lock icon.

We don't need new protocols or even changes in old ones so much as we need Mozilla, Microsoft, Google, and Apple to sit down and come up with a standard set of UI idioms that will allow users to quickly and visually "authenticate" a domain name from the cues made available to the browser.