DanCoulter

Using this plugin, you can easily and automatically backup important parts of 
your WordPress install to Amazon S3. Amazon S3 is an extremely cheap service 
that is easy to set up. For pennies a month, you can make sure that your 
important files will be kept safe.
Important caveat: this plugin currently has to be run on a linux server. 
Also, the wp-content/uploads folder has to be server-writable or it won’t be 
able to create the zips for backup.

WP S3 Backups

Automatically back up important bits of your WordPress install to Amazon S3.

Using this plugin, you can easily and automatically backup important parts of 
your WordPress install to Amazon S3. Amazon S3 is an extremely cheap service 
that is easy to set up. For pennies a month, you can make sure that your 
important files will be kept safe.
Important caveat: this plugin currently has to be run on a linux server. 
Also, the wp-content/uploads folder has to be server-writable or it won’t be 
able to create the zips for backup.
For full info and installation instructions, visit http://www.webdesigncompany.net/automatic-wordpress-backup/

WP S3 Backups vs Automatic WordPress Backup