Props to Dylan who sent me this piece of semi-useless trivia:

Post Code Power

Discover how different postcodes live, starting with your own. Brought to you by News Limited Community Newspapers, Postcode Power shows you just how well community newspapers know different postcodes and how you can use that knowledge to target any audience more effectively.

How awesome.  Not a lot of variation between suburbs, but some of them are very telling and closely match my experiences.