Secure GnuPG Form is a Web form that sends encrypted email and attachments using GnuPG, without the sender needing to have GnuPG installed. Versions are available with Recaptcha.net support and two-factor authentication using a username and password and the free PhoneFactor.com service.
h2H Messenger is a secure messenger client that uses PHP OpenSSL functions, mcrypt, and PHPSecLib to encrypt messages at-rest using RSA keys. The user only creates an account and the application handles the public key generation, key management, key exchange, and encryption and decryption of messages. There are no algorithms or key sizes to choose. It uses strong standards (AES 256, 4096 bit RSA Keys, SHA1, SHA512, etc.) in the background, and requires two-factor authentication using a code sent via SMS or using Asterisk.