The MIT PGP Home Page provides information about PGP as well as how to obtain PGP from MIT

Private Idaho is an internet privacy utility for Windows. It simplifies using e-mail with PGP, anonymous remailers, and nym servers, providing you with more electronic privacy. Private Idaho is free, with no shareware or registration fees. Its purpose is to encourage the wide spread use of strong cryptography and provide users with a greater level of on-line privacy.

MacCTC is a simple text editor that will perform encryption and decryption operations. It has a AppleEvent interface to Eudora (-Lite or -Pro) to allow the direct sending and receiving of e-mail at minimum effort. It is commerically usable freeware.