If you are looking for some Work For Accommodation options WWOOFING tends to be the most popular and well known option in New Zealand. But you also may find Help Exchange & FHINZ to be useful options.
Very similar to WWOOFING, Help Exchange offers work in exchange for accommodation opportunities all over New Zealand. Most likely these will be on farms but they may include cafes, child care, horses and hostels.
There are two types of membership options. A free membership allows you to create a profile of yourself and hosts can contact you directly. By upgrading to a premier membership for a small fee you can directly contact hosts.
Once again a similar concept to WWOOFING, Farm Helpers In New Zealand (FHINZ) offers work in exhange for accommodation all over New Zealand. The key difference between FHINZ & WWOOFING is that farms do not have to be organic. So you may be working on a sheep, beef, dairy, deer, chicken, cropping or vegetable farm. FHINZ could be a great way to gain experience on a farm before applying for paid positions.