The other main site for jobs in NZ is the Jobs section of trademe.co.nz (who themselves are a pretty cool little company to work far, or so I hear). As far as startups in particular I don't know of any particular website or anything that NZ startups accumulate around, although you might find the NZ Startup Digest interesting (I found it on HN at some stage): http://us1.campaign-archive1.com/?u=92be899ef5a892c60b4a6cd9...
I would recommend you also look more specifically into where in New Zealand you want to live, or at least what sort of lifestyle you want. You can easily find a technology job in Auckland or Wellington (startups also tend to gravitate towards these cities), but that comes with higher costs and a certain degree of the rat-race lifestyle. There are small local companies and startups in the provinces, but pay (and costs) will be lower and opportunities are much fewer and far between.
I myself just moved out of the provinces into Wellington, and so far i'm enjoying being in a bigger pool of developers and having more things to see and do in general, but I know people who have made the opposite move as well.
Feel free to contact me if you need more info.
EDIT: Of course if you manage to get a remote job, it won't matter much where you live, provinces or otherwise :-)
http://www.idealog.co.nz http://unlimited.co.nz/
Few other high profile companies: http://www.vendhq.com http://www.silverstripe.com http://www.optimalusability.com/ http://www.rakon.com http://www.starnow.com http://www.smallworlds.com