pingfs is a filesystem where the data is stored only in the Internet itself, as ICMP Echo packets (pings) travelling from you to remote servers and back again.
It is implemented using raw sockets and FUSE, so superuser powers are required. Linux is the only intended target OS, portability is not a goal. Both IPv4 and IPv6 remote hosts are supported.
To run pingfs you have to create a lists of hosts to bounce your data on. Hosts far away give greater latency and bigger storage capacity, while very close hosts lower both properties by around a factor of 1000.
The first attempt at a pingfs implementation was using haskell and started back in 2011. This code got basic writes working before it was abandoned (archived here). The current C implementation was started in early 2013 but did not do much until the summer 2015, where it got completed after being linked to by hacker news. Note that there is a different similar project also named pingfs here.
Enjoy pingfs responsibly.
Get the code at the github page.