Here's one that I used with some sucess for a while but then went off on a tangent.
Sydney and Melbourne only Sat only. Staring at race one,(then race 2 if no selection etc) and working down the TAB numbers (from no 1) the selection is the first horse that won both it's last two races. So a maximum of 100 bets per year. Just for fun todays bets are SR3-3 and MR1-2
NB The selection is the first horse that won its last 2 RACES (not 3 more)