P2P social network application Pandora.
Pandora affords functions of instant messenger, audio and video chat, encyclopedia article and file exchange, trading platform, payment system, distributed development system and vote system. Pandora has its own binary protocol, uses a cryptography and a web of trust.
Pandora is not yet another "geek thing". It is designed for ordinary people, has a graphical user interface (GUI) and works "out of the box".
More info about Pandora:
Installers for Windows and Linux (alpha versions):