The Freenet Project
Freenet is free software which lets you anonymously share files, browse and publish freesites (web sites accessible only through Freenet) and chat on forums, without fear of censorship.
Secure video calls, conferencing, chat, desktop sharing, file transfer, support for your favorite OS. Jitsi can encrypt your calls using the innovative ZRTP.
Pidgin + OTR
The Off-the-Record (OTR) plug-in designed for use with Pidgin ensures authenticated and secure communications between Pidgin users.