Hello,
I'd like to suggest a portable app to add to this website: FreeSecurity.
http://www.canudo.net/derelict/freesecurity
FreeSecurity is an easy to use freeware application that allows you to use encryption to secure your files and safeguard your privacy. FreeSecurity uses strong 128-bit AES encryption, the next generation US Goverment standard for protection of classified information. Additionally, it offers compression on the encrypted files.
Runs on Windows, Linux and MacOS, with no need to install, just double click the file. The only requirement is that you have Java properly configured (i.e. .jar file are associated with the Java Runtime Environment).