Two Factor Auth (2FA) - List of websites and whether or not they support 2FA
Authy - Best rated Two-Factor Authentication smartphone app for consumers, simplest 2fa Rest API for developers and a strong authentication platform for the enterprise.
X (Twitter) - Connect with your friends and other fascinating people. Get in-the-moment updates on the things that interest you. And watch events unfold, in real time, from every angle.
Nitrokey - Email Encryption. Encrypt your emails with GnuPG, OpenPGP, S/MIME or your favourite email client.
Rapid 2FA - A painless way to add two-factor authentication to your site
YubiKey NEO - Hardware-based authentication