I needed a street address/postcode web service for one of our projects. Google then released their Appengine product for testing. What a good opportunity to play with their new service.
It's based on data extracted from the NZ Post PDF files.
There's currently four delivery methods; /plain/, /html/, /json/ and /xml/. They all require the "q" query argument, the XML and JSON methods also support a "full" argument which adds the lat, lon, accuracy and numbers fields.
Here's an example using a jquery autocomplete plugin I found via Google.
Hadley Rich from nice technology