Geeklist - Shows how long it would take for your password to be cracked in the sign up form.
Mixpanel - When changing your password, the field for the current password has an old style key, and the new password has a modern key.
/via Timothée Boucher
Facebook - When you type in the correct password with a slightly incorrect username, it will prompt you with the correct username and ask you to retype the password.
Facebook - If you try to log in with a wrong password, Facebook will send you an email with an Instant Login link.
/via Hannes Struß
Twitter - On the mobile version, the error message lets you know that typing on a phone stinks.
Twitter - After you change your password, the system reminds you how many apps have access to your account and lets you review them.
/via Rolando Murillo
Gmail - When attempting to sign in with an incorrect password, it reminds you how long ago it was changed.
/via Garrett Miller
Facebook - When you try to post your password on Facebook it turns into asterisks. /via jan the funny guy!
UPDATE: As it turns out, this doesn’t work. Sorry about that! Keep your passwords save folks and don’t accept candy from strangers.
Facebook - When entering an old password, it tells you when/where you changed it, and offers you to request a new one, or try again.