G'day Sam,
Hope you're enjoying the sunny climes of New Zealand; there are plenty of lovely places to see in there. Being a Kiwi, I thought I might suggest a few places to visit.
Places of interest up north include 90 Mile Beach, Bay of Islands.
Further south is Rotorua (geothermal wonderland). Rotorua is rather touristy; however there are plenty of geothermal sites to see outside of the city, as well as one in town. You will probably need your own transport, although alternatively I think there is a bus that takes back packers all over New Zealand. Then there is Lake Taupo, which is a lovely, tranquil place with a good camp site, which has its own thermal pool (unfortunately the name of the camp site escapes me at the moment).
On the east coast there is the first city in the world to see the sun: Gisborne. Not too much happening there, but if you are into beaches and surfing this is the place for you.
To west of the North Island are the Waitomo Caves; plenty of adventure there, such as black water rafting (you go through the caves on an inner tube in the pitch black - not for the faint hearted). Then, of course, there are the glow worms in the Waitomo Caves themselves. Wellington, the capital, is a cultural city, plenty of clubs and places of interest.
To get over to the South Island, the inter-island ferry is your best bet; you see some beautiful scenery as you pass through the Sounds. In Kaikoura you can swim with the dolphins, and whale watch. Outside Christchurch is a lovely place call Hamner Springs and I know of a good winery down in that neck of the woods as well, if you're interested.
And finally, in order to tantalise your traveller's tastebuds, you should try a hangi (traditional Maori food, cooked in the ground), hokey pokey ice cream, pineapple lumps and of course Steinlager if you are a lager person - it's the New Zealand brew (although DB Export tastes much nicer, in my opinion.)
Happy travels.
Maria Harvey