Due to the amount of competition in the backpacker industry hostels in Australia are of a very high quality. Chains such as Base are now producing boutique budget accommodation so you will have no problem living the high life whilst still saving money!
VIP - The largest hostel chain in Australia with a minimum of $1 off each hostel you stay at on production of your card. Membership also gives you discounts off travel passes and activities. Rather than own the hostels, VIP operate as a marketing tool and so be aware that hostel quality and facilities can vary greatly.
Nomads - Another big operator of hostels in Australia. Membership gets you either $1 off a night or your 7th night free. You also get discounts off travel passes and activities and cheap phone calls thrown in as well! They currently offer over 600 discounts in Australia.
YHA - The Australian flavour of the Hostelling International Group. Currently operate 140 hostels within Australia. Membership can be used in hostels around the world and they offer 800 discounts in OZ alone! Using a membership card at a YHA hostel should bring you around $1-3 discount.