Thanks Falko, I'll give it a try. It really does seem silly to have to add each new DB I create - but if it works I can't really complain!!
I've got automated sql dumps being forwarded out to a secondary machine anyway, so perhaps that would be better than worrying about replication issues.
From what I can see, replication is a great way of having 'real time' backups, but mysqldump seems to be more reliable as a way of backing up all the data in a DB without having to worry about specifying tables etc.