For big backups, I can't recommend cloud storage, but for important files, I always leave a copy on Dropbox.
Although recently I've run out of free gigs and I'm not sure I want to go for the paid solution, as it's quite expensive.
I've just discovered Copy, a new cloud storage solution that offers a lot more space than Dropbox for free.
You get 15 Gb for free to start with, and another 5 Gb for free if you sign up with this referral link:
https://copy.com?r=yx223v
There you go, sharing the good tip...Enjoy!