Chris Simon's Cicada Central has photographs and information on almost all the New Zealand cicadas, and also has sound recordings for most of them too. Click on the second link down "electronic field guide to the cicadas of New Zealand" to access this.
She also has a location database which you can use to find where different cicadas are found. It won't map search that have over 200 specimens so it works best for less common cicadas.
The main Landcare Researach website has a good photograph gallery of the New Zealand cicadas.
It also has helpful identification factsheets but note that the identification key on this page doesn't work - to access the key use this webpage instead.
Cicada Mania is an American website, but it has lots of good general information, and regularly lists new research that people are doing, what cicadas are coming out where etc. They have an active facebook page too.
Contact us at cicadasofnewzealand@gmail.com.