Dropbox keeps a 30-day history. And you can pay for a forever history.

This, of course, is precisely what Time Machine does on a Mac. An alternative is Dropbox: move all your working files into/under the Dropbox directory, and they will be automatically sync-ed to the cloud, as they change. If you disconnect from the internet, it remembers (or figures out) what to do when you reconnect. I do both: Dropbox for immediate and continuous backups, and two Time Machine drives I alternately connect once a week or so; one kept at work and one kept at home. Belt and two suspenders with geographic diversity. As far as freeware goes: you get what you pay for. $100/year for a 1 TB Dropbox is well worth it, IMHO (and I want to help keep them in business).