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Yes, Owncloud. Easy to install:

Git and Sparkleshare offer something that is IMO much close to dropbox than owncloud.

Other people have offered some more "modern" options, but SFTP and WebDAV over SSL still work very well.

Try git-annex and git-annex-assistant; it doesn't even require a central server.

Try Tonido (http://www.tonido.com). It is not open source though.