These are KMZ raster versions of the Australian 250K dataset suitable for GoogleEarth and CustomMap compatible Garmin units. The data is the 2008 Mapsheets available from MapConnect or on DVD from www.ga.gov.au. It is released under the Creative Commons Attribution 3.0 Australia Licence. - please respect the licence.
You should first look at the Map Index to see the sheets that are currently available (in green), then grab the ones you need from the here. I have currently converted all of VIC/NSW/TAS and small portions of SA/WA/NT - please contact me if there are other areas you require and I'll add them to my build list.
Standard mapsheets come out at 16 tiles so you can generally put 6 mapsheets onto a Garmin device (there is an annoying 100 tile maximum for Garmin CustomMap) but the special sheets around the coast vary from 11-35 so you may only be able to use 4-5. Enjoy...