Lifehacker has tried virtually all of the major airport buses in Australia, so I have no hesitation in saying this: the Airport Flyer service that runs in Wellington is hands-down the best I've ever seen.
For a public transport junkie like me, the Airport Flyer was the obvious option when hitting New Zealand's capital for Linux.conf.au 2010. Like airport services everywhere, it runs frequently (every 15 minutes) and at a slight premium to regular buses ($8 for a one-way ticket to the CBD). Unlike many airport services, the bus itself is extraordinarily comfortable, with leather seats and an astonishing amount of leg room.
What really made the bus work for me, though, was the provision of free Wi-Fi onboard, which I hooked into with my BlackBerry before catching up on Twitter. I was excited enough at the news that Adelaide was trialling a bus with free Wi-Fi; to have a regularly scheduled one has got the trip off on a really great note.
Even if you're not hitting New Zealand soon, save money (and greenhouse) gas with our guide to airport shuttle services in Australia.