I searched to forum for it, but obviously it hasn't been posted already:
http://www.nzstamps.com/The online catalogue is a very useful tool if you're trading/swapping NZ stamps with someone who doesn't own a "real" catalogue. You can give him/her precise numbers, you're searching for and don't have to rely on descriptions ("I was looking for the stamp with the mountain." "But it does have a mountain on it." "Yes, but it's the wrong one..."

).