A few more interesting projects.

Hive2Hive is another open source distributed P2P file sync program. It is written in Java and has an extendable API.
http://hive2hive.org/
https://github.com/Hive2Hive/Hive2Hive

YaCy is a P2P search engine.
http://yacy.net
https://github.com/yacy/yacy_search_server

A port of the Syncthing synchronization protocol in Go and Swift.
https://ind.ie/labs/
https://source.ind.ie/project/pulse/tree/master
https://source.ind.ie/project/pulse-swift/tree/master

ClearSkies is a open source BitTorrent Sync clone.
https://github.com/jewel/clearskies

SyncNet is a decentralized browser built on top of BitTorrent Sync and (soon) Colored Coins.
https://github.com/jminardi/syncnet

Installing BitTorrent Sync on the Raspberry Pi
http://jack.minardi.org/raspberry_pi/replace-dropbox-with-bittorrent-sync-and-a-raspberry-pi/

A collection of peer-to-peer decentralized projects. Categories: Web, Communication, Platforms, Finance, Streaming and Storage.
Can someone with a GitHub account please contact Moshe Simantov to get NEM added to the list? https://gist.github.com/moshest/aea88f152fac89e1c526

Some cool stuff here