TestSubject - Test how your email subject line displays on mobile devices.
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.
Canned Emails - A minimal site with prewritten emails
Two Factor Auth (2FA) - List of websites and whether or not they support 2FA
analyze.email - Test the spam-y-ness of your emails
Google Titan - A 2FA device to protect yourself from hackers