Popular and, probably, the best instant messaging client for you Mac.
Jitsi (previously SIP Communicator) is an audio/video and chat communicator that supports protocols such as SIP...
Handy tool for modifying the access-control on one's Mac.
Chromium-based web browser with enhanced privacy and security options.
Write secret messages to your friends. Only you and your friends will be able to read them! Jibber Jabber is freeware.