Sendmail-TLS is a wrapper for Sendmail which allows for clients to make a secure (SSL) connection to their mailserver as described in RFC 2487. The connection is internally forwarded to sendmail and does not require sendmail to be running on port 25. Clients which support this currently are Netscape Messenger, Microsoft Outlook, and Microsoft Outlook Express.
pyCA is a project to create Certification Authority in Python. It will generate a CA certificate hierarchy and initial CRLs, generate certificate requests with widely used web browsers, provides a search tool for client certificates in the OpenSSL certificate database, download of client certificates/certificate revocation lists with appropriate MIME types, storing all certificate data in LDAP repositories, scripts for the handling of the certification process on a non-networked system holding the CA's private key(s) and fairly easy configuration based on the OpenSSL configuration file.
pks-commands.php3 allows your Web server to search and add PGP/GPG keys from the public keys out there. It takes the TCP 11371 port connection and does it all on the web server. It is good in environments where the client machines are unable to get to arbitrary TCP ports (such as behind tightened firewalls).
PGP Pipe allows encrypting a data stream of arbitrary length with the IDEA chipher from PGP. It is fast and usefull for secure backups on tapes or across the network. To prevent that this program is considered "strong cryptography", the encryption routines are NOT included, so you have to get the PGP source to compile it.