Open-source NAS (OS image)

• FreeNAS – http://www.freenas.org/
• NAS4Free – http://www.nas4free.org/
• NexentaStor – http://www.nexentastor.org/
• Openfiler – http://www.openfiler.com/
• OpenMediaVault (Debian-based) – https://www.openmediavault.org/
• Rockstor – http://rockstor.com/

Open-source NAS (package)

• OnionShare – https://onionshare.org/
• ownCloud – https://owncloud.org/
• pydio – https://pydio.com
• Seafile – https://www.seafile.com/
• droppy – https://github.com/silverwind/droppy

Technical Articles

• Dropbox Tech Blog – https://tech.dropbox.com/
• Windows Directory Change Notifications – http://msdn.microsoft.com/en-us/library/windows/desktop/aa365261(v=vs.85).aspx
• [stackoverflow] Watch for file modification in C++ – http://stackoverflow.com/questions/931093/how-do-i-make-my-program-watch-for-file-modification-in-c