See also: Distributed filesystems
A searchable, distributed, encrypted datastore. It is programmed in Python and can therefore be used on a large variety of platforms. The project appears to be inactive, though the Web site as of April '05 claims not to be dead. The user interface uses wxWindows and it is the successor to Mojo Nation.
Mnet has not been designed with anonymity as a goal although it is not fully anonymous yet. When a file is uploaded "into" the network, it is distributed among many different machines (and not your own) certainly offers some deniability at least. Furthermore, the network is censorship resistant because files are redundantly split across different nodes, shutting one node down will never be enough to get a file taken off the network.
Screenshot of version 0.51, showing the search result window