well TABsportsbet and sportsbet.com.au are two different places you know that? Both are awesome in my opinion! TABsportsbet are the ones offering what i'm talking about here.
They both do the line/over and under double for AFL and NRL too but sportsbet.com.au don't do it for the USA sports. only TAB
but with afl and nrl doubles they come in really close to game start time as the aussie books seem scared of putting over/unders up early for some reason but they can put USA over/unders up 24 hrs before....annoying