An Annual pass is a magical key to the 'World' which everyone should have!!
There is more info here (including the phone number). If you plan on visiting for anymore than 5 days you can end up saving the entire cost of the ticket through various discounts on tours, rooms, meals etc - I have one and love it to pieces. I used it at the beginning of June and plan to go back next year just before it runs out - I used it for 8 days this visit and plan on another 8 next time. It saved me $100 a night on AKL for 8 nights and loads of other perks as well. I really cannot recommend them enough!!