I don't know how long its been around but found this App while looking for a PDF Scanner for the phone.
Once installed you can find each locations for the PO, LPO, Red/Gold street boxes and their addresses.
I think someone once asked if there was a way to find where all the Red Boxes are... well, here's the answer!
Click on a Red locator button and you have the address for the Box.
Click on the PO symbol and you have the Opening hours.
Click on "Find a Postcode" and start typing the name or the code and it lists the postcode you need or all the localities that use the postcode you typed - for example my area of Goulburn lists 45 localities under 2580.