Virgin, you apply direct at the website.
Jetstar use Westaff and advertise in the papers every month or two (also can be found on
www.careerone.com.au)
Qantas use Workforce International.
Sunshine Express -
www.sunshineexpress.com.au
You also have:
Australian Airsupport (Freedom Air, Emirates, Pacific Blue)
When I worked there they recruited direct and were doing the ramp side of things. Their phone number is in the phone book.
Hope this helps...