Here's a list of some nifty cryptography/
- socat - multipurpose relay; think netcat gone wild -- we used this recently to tunnel UDP DNS queries over ssh
- cryptcat - netcat with twofish encryption (the Debian package adds a man page)
- rsyncrypto - partial transfer-friendly encryption (modified CBC for smaller change windows similar to gzip; less secure than regular CBC)
And a pretty unrelated but useful Red Hat Magazine article on the new yum-security plugin.