RetroShare is a open source cross-platform, private and secure decentralized communication system. It lets you to securely chat, share photos, videos, and more, using OpenPGP to authenticate peers and .
Calypso, formerly Kommute, is a cross platfrom file sharing client using the anonymous network MUTE. Developped using C++ and Qt. For windows and linux, portable to other environments. You can try it by following the installation instructions below.
The project is no longer developed. Last version, 0.24, released in May 2010, can be still downloaded from the official website.