For me it's been something of a Holy Grail: the perfect backup regime. But with high-speed always-on Net access it's never been easier to ensure your data's backed-up and safe. Because let's not forget Someone's First Law of Data: "it doesn't exist if there's only one copy of it."
Anyway, there are several free online backup services available, and my fave is idrive.com. Free for up to 2 Gb, and reasonably priced for 'unlimited' (150gb in reality). Their system tray application is good since it can be used to define scheduled back-up 'sets' - so you could backup automatically any changed files on a daily basis - if not as and when they change.
So at least I know that the next time a hurricane or earthquake hits, my data is safe!