The Time Capsule makes it quite easy to plug an external USB drive into it and "clone" your backup image onto said drive.

So combining a Time Capsule and a of couple cheap external HDs into a multiple-rotating-offsite-backup-drives scheme is pretty easy.

One bonus is that your computer can be off/sleeping while the TC makes the clone - very handy if your main computer is a laptop which might not be present while the cloning is being done.