Remote Database Backup
If you have a consistent connection to the external source then setting up replication would be the way to go.  This way you ensure that all changes are automatically sent to the 'backup' (aka slave) server.  You could still run a regular backup script to dump the data to an external HD as a failsafe in case someone 'drops' all the tables int the database.  The book High Performance MySQL is a good source of information on replication setups.