I've just released some scripts and stylesheets for the Geoscience Australia Australian Bathymetry and Topography Grid data.
Here are some samples of the final outputs. (also available as a layer on my demo slippy map)
These images based on data © Commonwealth of Australia (Geoscience Australia) 2009, which was released under the Creative Commons Attribution 2.5 Australia Licence,
http://creativecommons.org/licenses/by/2.5/au/
.
The code I used to produce these images is CC0, so as far as I am concerned you are free to recreate them under whichever license is compatible with the upstream data. If you just wish to use these images, I license the ones you see here (so only if you grab them from here, rather than re-rendering them) under the Creative Commons Attribution 3.0 Australia license,
.http://creativecommons.org/licenses/by/3.0/au/