PUBLIC MARKS from fredbird with tags web-app & password

This is a distributed identity system, but one that's actually distributed and doesn't entirely crumble if one company turns evil or goes out of business. An OpenID-enabled site/blog lets you authenticate using your existing login from your homesite (whether that's on your own server or a hosted service) without giving away your password to the 3rd-party site you're visiting, or making a new account there, or giving away your email address. And it's secure, and can run entirely in the browser without extensions, without moving between pages.