I am considering doing this on my web: no user-selected passwords, account creation and login would look the same. User gives an email address and then they would need to prove their own that email address by clicking on a link in a sent email. The link will set a cookie and the user is logged in while the cookie is valid. No need to rely on 3rd party authentication service, so it is more secure if the link in the email is only valid for a short time.