Moraki Head at the light hose is a great spot for bluecod, but the couta can get real thick at times, to the point of eating everything that you throw in the water.
By far the best rock fishing I have had is down in the Catlins area.Bag limits of bluecod(kilo plus) as well as trumpeter and other fish. Wont say exactley where I fish there as looking and being rewarded with results is most of the fun.
I would say that there are countless good spots that are teeming with fish, but I havent got around to fishing them yet. Just go and have a look and remember to watch the water at all times as this is a rugged and dangerous part of the coast.