The Birth and Marriage certificates are also gold mines, not only in NSW and New Zealand but also in Victoria.
As I have only ever needed BDMs from these three I am unsure of the other states but they could be as useful.
You must remember that NSW, the first settlement/colony was set up initially for convicts and I understand that these and other records were meticulously maintained in order to keep track of the convicts. In NSW you can go right back to 1788 when the First Fleet arrived.
My two are well documented I wish I could find them in England and on the IoM before their trials but several years of searching has produced absolutely nothing about births or marriages.
Peter
Melbourne