The ABKey plugin provides a nice add-on for Address Book if you are using GPG. When used together with the GPGMail plugin for Apple Mail, it also manages for each contact whether to send email by default signed or encrypted:
The ABKey plugin provides a nice add-on for Address Book if you are using GPG. When used together with the GPGMail plugin for Apple Mail, it also manages for each contact whether to send email by default signed or encrypted: