Back in the days, before cloud-based services like Dropbox or iDisk, I used to be a big-time user of iFolder. Desktop file-sync for all kinds of platforms with central versioned storage complete in your own control. Too bad current iFolder development is as dead as can be since 2006. The downside on the current cloud-based storage services is that the central storage in maintained and in control of a third party, to which you trust your data to be safe. SparkleShare is a promising new FOSS project that brings new life to iFolder concepts. A friendly desktop client for all common platforms allowing you to store and version files to a SSH or Git based backend. SparkleShare is currently available as an open beta version of the client software for Mac and Linux.