Are there any required vaccines to travel to New Zealand?
There are no required vaccines to enter the country, either as a visitor or with a work visa. In the second case, along with your application you will be asked to provide a couple of medical tests and in some cases a chest X-Ray (but only if you come from a high incidence TB country).
If you're just visiting, odds are you'll be fine. However, there is a small risk of contracting Hepatitis A from contaminated drinking water, and Hep B from sexual contact, needles/tattoos and the like. You'll also want your regular shots to be up-to-date - tetanus, MMR, polio and so on.
More information is available on the CDC website's page for New Zealand.
However, as with all medicine, DO consult with a medical professional before choosing to take/reject medicine.