Dropbox - Online Sync and File Sharing

FTPbox - FTPbox is an open-source application that allows you to synchronize your files to your own host...

ownCloud - ownCloud is an open source project enabling businesses to host their own cloud storage while maintaining regulatory and compliance needs.

Syncany - Syncany is an open-source cloud storage and filesharing application.

Box - Box offers secure content management and collaboration for individuals, teams and businesses, enabling secure file sharing and access to your files online.

FTPSync.pl - FTPSync.pl is a PERL skript to synchronize a local directory tree and a remote FTP directory tree.