Okay, my information may be a little out of date, but I've done a bit of beer tourism in the South.
So in Dunedin is Emersons which is one of New Zealand's bigger (and excellent) breweries. I haven't been there myself, but the beer is awesome.
Nelson Bays region is loaded with breweries and is the centre of NZ's hop growing industry;
Blenheim: Renaissance/8 Wired (two breweries, same premises), Pink Elephant (We weren't able to visit this though), Moa (Not my fav, but very popular at the moment, also based on a winery so two birds one stone).
Nelson: The Freehouse is an excellent bar in an old chapel, Founders Brewery (Based in an historic park area, a bit weird, but the brewery is good). McCashins (where New Zealand's craft beer begun. Was the home of Macs, but has been reclaimed by Macs original owners, the McCashin Family, and is brewing under the label Stoke now).
The Moutere Inn is a funny little tavern (and self proclaimed oldest pub in the country) where you can spend the night, has great beer and some old school lodgings when I was there.
Finally, the Mussel Inn: A must visit. Quite out of the way, but an awesome brew pub near Takaka, Awesome vibe and great beers (including the famous Captain Cooker Manuka Beer). Be warned however, they don't take kindly to mobile phones.
Some photos for the curious.