These are just a few resources I have found online which may prick your interest.
Contributions on Northland Cemetery records to be found on Internment.net.
New Zealand Genealogy Online Data New Zealand Cemeteries. In addition to an extensive list of links to the many council operated and other cemetery databases online, one useful resource I have noted is a memory tree.co.nz, which purports to record over 90% of all deaths. I ran a couple of checks using the Northern Advocate but was unable to track anyone who had died prior to 2006. Having said that, I can see it will have some uses. Another is Tributes Online .
The Genealogical Computing Group also has a link to various cemetery records as does the New Zealand Government On-Line Genealogy Resources and the Norsewood Cemetery Project.
A page devoted to Northland and Bay of Islands Genealogy has some useful links .. especially the various cemetery links and the link to the War Memorials Register, Northland. PS: There are also links to other registers throughout the country in the sidebar.
The Whangarei Libraries Family History page and especially useful the libraries’ pointers to all that is available in their Microfiche Collection . I recall using this many years ago and if my memory serves me right, Births, Deaths and Marriages can be searched alphabetically. There is a lot of information to be found here including the New Zealand Expeditionary Force World War II Nominal Rolls.
A listing of Maori Cemeteries in New Zealand.