TimePreserver lets you archive Time Machine backups
Dalamser has released TimePreserver (http://www.dalamser.com/TimePreserver/index.html), an US $35 app for Mac OS X 10.5 and higher that lets you make archives of your Time Machine backups stored on a Time Capsule. A demo is available for download.
To user you attach an external disk to your Mac, run TimePreserver, and then store the disk away from your Mac and Time Capsule. Re-attach the disk and run TimePreserver to update the archive. You can use multiple external discs in rotation to provide extra protection. A minimum of two is good, always keeping one in a different location.
Read More