Continuum

Continuum backup software complements Time Machine, for simple, safe, and secure off-site backups.
Continuum stores up to 10 GB of compressed backups on your choice of remote storage: a MobileMe iDisk or Amazon S3 storage bucket.

Backups are encrypted with your secret passphrase. Manually perform backups, or let them run each night automatically. Continuum automatically checks for new versions, and updates itself by default.