Postcode API is a free service that allows anyone to easily lookup Australian suburbs and postcodes based on various criteria.
Version 0 is now available in public beta.
$ curl http://v0.postcodeapi.com.au/suburbs/3066.json -H 'Accept: application/json; indent=4'
[
{
"name": "Collingwood",
"postcode": 3066,
"state": {
"name": "Victoria",
"abbreviation": "VIC"
},
"locality": "HAWTHORN",
"latitude": -37.8,
"longitude": 144.9833
}
]