Dark Order - 5000 years of Violence (Great Slayer-esq thrash mixed with some death elements
Alchemist - Lunasphere , Spiritech , Organasm (one of the MOST ORIGINAL bands on the planet...umm Psychedelic metal...mized pretty much every genre and adds even more no metal elemets to create a sound all it's own
Atomizer - the end of forever (Old Schol black metal ...with a bit of humour thrown in for good measure , tracks include "Now thats fuckin evil" , "the only good human "is a dead fucking human" etc)
Black Steel - Destructor (80's trad/power metal in the vein of ManowaR , Hammerfall , Preist , Maiden etc)
Cryogenic - Ego-Noria (Great Agressive Post-thrash metal...chuggin riffs , angry vocals
Choke - Smokin' tailpipe action (Groovy grind-core....think blood duster with out the blast beats...similar lyrical themes ...)
Enforce - Campfire Night (Death/thrash metal...fuckin awesome stuff)
Mortal Sin -Mayhemic Destruction , Face of despair , Rebellious Youth , Revolution of the mind (Legendary Aussie thrash bands...got pretty big back in the day)
Allegiance - Destitution , Skinman(another huge OZ thrash band...were on the brink of greatness and then the ass fell out and they dissapeard...don't ya hate that)
SyZyGy - Prominance(Instrument Prog rock/metal group...fuckin awesome stuff)
Umm thats all i can think of off the top of my head...but there's a shit load more great aussie metal out there