SpiderOak as a Secure Alternative to Dropbox – ProfHacker – The Chronicle of Higher Education
http://chronicle.com/blogs/profhacker/spideroak-as-a-secure-alternative-to-dropbox/34305
and some more sync things
http://www.carbonite.com/en/ $59 per computer per year
http://rsync.net/ $0.80 per GB per month
https://www.jungledisk.com/ 5GB free
https://spideroak.com/ 2GB free
http://www.livedrive.com/ForHome/Backup