NOTE:  DID NOT WORK FOR ME - DRIVE WOULD NOT BOOT ON EC2 INSTANCE SO JUST FOLLOWED THIS INSTEAD:
http://atodorov.org/blog/2014/02/07/aws-tip-shrinking-ebs-root-volume-size/
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(Original Paste Below)
Lets you backup a running instance of linux. (Should stop services like mysql first for good measure...)

This command taken from archlinux article found here:
https://wiki.archlinux.org/index.php/full_system_backup_with_rsync

rsync -aAXv --exclude={"/dev/*","/proc/*","/sys/*","/tmp/*","/run/*","/mnt/*","/media/*","/lost+found"} /* /path/to/backup/folder

Perhaps Better?:
rsync -PazSHAX --exclude={"/dev/*","/proc/*","/sys/*","/tmp/*","/run/*","/mnt/*","/media/*","/lost+found"} / /path/to/backup/folder