Most web sites ask for a password when you register.
After logging in, you can access the site until your session expires.
When you forget your password, you can request an email with a link to a password change form.
NoPassword factors out the password from this process. You register with an email address and receive a link that gives you a session on that browser until you log out.
If you ever need to log in from somewhere else, you can request another email with a link that will log you in wherever you are.
Check out the code on Github.