Mysql-s3-backup is a project mainly written in Ruby, it's free.
Perform full and delta backup of mysql databases
Perform a full or delta backup of your entire mysql database to S3.
Requires a UNIX like environment with xdelta3 and bzip2 installed.
Run as a standard user. Requires the file ~/.server_config in the following format:
s3_key: s3_secret: mysql_root_password: days_between_full_backups: 14