Tahoe-LAFS is a Free and Open cloud storage system. It distributes your data across multiple servers. Even if some of the servers fail or are taken over by an attacker, the entire filesystem continues to function correctly, preserving your privacy and security.
ownCloud gives you universal access to your files through a web interface or WebDAV. It also provides a platform to easily view & sync your contacts, calendars and bookmarks across all your devices and enables basic editing right on the web.