Datto is selling this new NAS that continuously backs up your data to the company's off-site servers. If your NAS crashes hard, they'll overnight you a new unit with your last backup already installed. It'll cost you, of course: $25 a month (discounts for longer subscriptions), plus the initial $600 entry fee for the 500GB device. That's too pricey for most home users, but could be useful for a business.
Then again, how often does a whole NAS die? The point of a NAS in the first place is that you'll likely — knock on wood — only ever lose a single drive at a time, giving you the opportunity to swap in a replacement before the whole thing goes tits up.
Product Page [DattoBackup.com]