Dolly Drive is a cloud-based backup solution that works with Apple's Time Machine. Once configured, Time Machine treats it as it would any backup volume. Additionally, Dolly Drive creates a local bootable backup, giving you both a local and an off-site backup of your stuff.
Version 1.2 increases the offline storage cap to a generous 2 terabytes. Also, incremental cloning improves the speed of that process, and a new multi-site grid infrastructure on DD's end decreases users' upload time.
I've been happily using Dolly Drive for half a year now. Prices start at US$5/mo. for 50 GB of storage and max out at $55/mo for 2 TB. As a bonus, users receive an additional 5 GB storage per month at no extra cost for every month that they remain a customer.