Ultralight super compact Syn Mat from Exped
I initially dismissed this ripper as beign too flimsy.
What I didn't know then is what it was like to use. As the hand of fate would have it I was "forced" into needing to use it one weekend, I was amazed at just how comfortable and easy to live with it is. It's now my mattress of choice, it's ridiculously compact and light.
The Ultralight Mat is about the size of two cans of beer and weighs less. I can blow it up by mouth in about 20 breaths and I've used it in some pretty cold conditions.
For the majority of Aussie applications the -4 rating is more than enough insulation from the creeping cold of the ground.