Dropbox

When it comes to cloud storage, it's hard to beat Dropbox. Although security is an often-touted concern with the cloud-storage behemoth, ease of use trumps those concerns. Ubuntu One is a distant second to the cross-platform, simple-to-use Dropbox. I'd put my Dropbox referral code here to get some free space, but I suspect our editor would frown on such a thing, plus you'd all likely flog me.