Client certificates - it’s like authorized_keys for your web browser. I’ve wanted this for ages. Passwords are so lame - insecure, hard to remember, just annoying all around. Even worse is the whole process of logging in; particularly on banks and other financial websites where they make you go through a multi-page wizard. Asymmetric key cryo is what it’s all about.
I look forward to the day when we all keep our private keys on a usb dongle, such that we can sit down at any computer and have instant access to all of the sites and services that we use.