[thelist] Calculating postcodes - Australia

[Tim Burgan]

Hello,


I've developed a site where a user can enter a postcode, and a list of 
registered clients on the website that are in or AROUND that postcode 
are returned.

I got the postcodes and divisions from Australia Post via their little 
$4 postcode booklet.

The problem is the if the user enters a postcode, for some postcodes it 
returns businesses in a postcode over the other side of the city, yet 
the neighbouring postcode doesn't show up.

I think this is the way Australia Post divides their postcodes.

I thought maybe Yahoo or Google would have a resource where you can get 
a postcode and return the postcodes in the surrounding 20km (for example).

How in the world can I do this?


Thanks

Tim