In reply to Sazzlecymru:
Unfortuately internet information is limited at best. The websites aready mentions have some information. in the deep south some of the crags/areas have their own facebook pages (i.e Dunedin and castedowns crag) which have a couple of topos of new routes.
A fairly good overview article was done by fiend a few years ago
http://www.ukclimbing.com/articles/page.php?id=24
In terms of other information sources just asking people on UKC is quite useful as you often get a reply compared to the NZ forums and you can gleam a lot of useful information albeit with lots of opinions too.
Guidebooks are variable depending on the area as a lot are out of print. some areas have locals guides available which are fairly good - wanaka, paynes ford and castle hill are good examples. The new queenstown guide is out later this month which will be good as trying to find an old guide or information over the past year has been like trying to find fairy dust.