The ECMA has a free basic membership, so there are active members from a few different continents, actually. There's a monthly published e-newsletter and forum (where I see you've joined--I replied!), and we've had articles, questions, and pictures submitted from people in Australia, Brazil, England, Canada, Croatia, Guam, and other places I can't remember right now. We don't currently have a lot in the way of paper-based materials (we like to stay as "green" and economically friendly to our members as possible), but I'd definitely encourage you to join, though of course I'm biased. 
I know you can also join the NMC and AFRMA as an overseas member and receive paper-based publications from the AFRMA, at least (and maybe the NMC too, I just don't know for sure one way or the other). I don't know if either of them has a free membership.
In some ways, it seems that Australia is like the US: a very big country with relatively few people who keep mice, so you're more spread out and thus you have many fewer shared resources overall than a place like the UK or the Netherlands, where people seem to live closer together. I could be wrong (I've never been to Australia), but that's the impression I get, and that's how it is in the US.
I know you can also join the NMC and AFRMA as an overseas member and receive paper-based publications from the AFRMA, at least (and maybe the NMC too, I just don't know for sure one way or the other). I don't know if either of them has a free membership.
In some ways, it seems that Australia is like the US: a very big country with relatively few people who keep mice, so you're more spread out and thus you have many fewer shared resources overall than a place like the UK or the Netherlands, where people seem to live closer together. I could be wrong (I've never been to Australia), but that's the impression I get, and that's how it is in the US.