> What irks me is that every OS in use today has support for strong cryptography and browser vendors could easily integrate that. We would no longer register for a website, we would simply upload our "Online Identity" or whatever we called it. This of course is just an id_rsa.pub with maybe name and email in the comment. The remote site stores the public key and the browser authenticates using the private key, stored securely in the keychain.

Like SSL client certificates?