The german OFF System handbook
I am the author of the UNofficial german OFF System handbook.
The OFF System is a new smart way to share files through a decentralized, world-wide online File System, building some kind of "distributed harddisk". Though not primarily coded as a file sharing app, it is very useful for that
The way it works isn't by hiding the content you are sharing, but instead by "separating data from meaning" - you will have to read the explanations on their homepage, to figure out what that means, I don't have the english skills to explain that.
Visit the OFF System at Sourceforge for further info..