Update : This plugin is not available any more. You may want to check http://pluginbuddy.com/purchase/backupbuddy/
We all have heard of importance of regular backups, but for a long time I had neglected it for my blog. But recently things happened that prompted me to take backups.
While I was looking for option to keep backups, I found Rackspace Cloud Files to be a very affordable option, this prompted me to write wpSimpleBackup a WordpPress plug-in that will take the backups to cloud files, and then I also added support to take backup to Amazon S3 or FTP to another server. But unlike my other plugins, this one is not free.
I can backup to all the cloud providers you mention and more using http://wordpress.org/extend/plugins/smestorage-multi-cloud-files-plug-in/. Why would I pay for your plug-in ?
Simply because even though plugin is free the service isn’t. You need an account from SME Storage before you can use it, which is not free. Also they do not provide simple restore and migration script that my plugin does.
You don’t just but a plugin, you buy complete backup solution for your blog.