Future Me - Send an email to your future self
Notopass - Share your accounts without giving username/password
Letter to Yourself - Send a physical letter to your future self
1Password - 1Password can create strong, unique passwords for you, remember them, and restore them, all directly in your web browser.
Timebomb Messenger - Send secret messages that open based on time or location 💣
ShareAccount - Share your account without giving out your password