You may know Microsoft Exchange and other commercial stuff for syncing and securing your data without handing it over to cloud providers and authorities - but there are some alternatives.
– Making Any Mac into a Calendar and Contacts Server - HOWTO
To protect this hint, in the event that the original site ever vanishes, I’ve also created a PDF from the how-to, and placed it on the hints server: http://www.macosxhints.com/dlfiles/CalDAV_and_CardDAV_howto.pdf
– Quite ok is Funambol https://www.forge.funambol.org
– And you should also consider using Sparkleshare ►http://sparkleshare.org
– Installing an online desktop on your own server is another approach. In the past EyeOS has delevered stunning features but today’s version seems to be more complicated to setup. It’s nevertheless worth a look : http://www.eyeos.org/open-source/download