https://flightbookings.airnewzealand.co ... MIGRATE2NZ
(This link doesn't always work depending on what else is going on on the website, so the info from it is below)
Promo Code: EMIGRATE2NZ
Save up to GBP160 on one-way Pacific Economy and GBP250 on one-way Pacific Premium Economy fares from the UK to New Zealand!
Sales period:
22 July 2008 to 31 January 2010
Travel period:
1 August 2008 to 31 July 2010
Terms & Conditions
Use the promo code EMIGRATE2NZ for up to a GBP160 discount off adult, GBP120 discount off child and GBP16 discount off infant fares booked in Pacific Economy class, or GBP250 discount off adult, GBP188 discount off child and GBP25 discount off infant fares booked in Pacific Premium Economy class, for flights between London and New Zealand. Offer only applies to one-way fares purchased from airnewzealand.co.uk. The discount does not apply to itineraries involving Virgin Atlantic (VS) flight numbers. Offer is valid for sale between 25 July 08 and 31 January 10 for travel departures between 01 August 08 and 31 July 10. Only one promo code per purchase is permitted. Promo code discount applies to the base fare only and does not apply to fuel surcharge, government fees and taxes. If a promo code booking is purchased and subsequently changed to travel outside the stated promo travel period a new fare will need to be purchased at the applicable fare level available. All rules and terms and conditions of fare type purchased will apply.
This only applies to one way direct tickets - unfortunately it won't work if you want to come back! But it has just saved my husband and myself £75 each (i.e. £150 total) off of the cost of our flights - definitely not to be sneezed at!