Something I was playing with and thought I would share from my website for testing your systems:

There were 24142 horse form lines in the database at this point in time.
There were 160 selections for the System
There were 100 which Lost (did not win race) for the System for a strike rate of 62.5%
You had to pay out $129.81 but brought in $152 after 5% commission. This means a Profit or loss of $22.19 or a percentage profit/loss of 13.87%

I called this the 3333 system because the rules are as follows:

Win Price <= 3
TAB Number <= 3
Barrier <= 3
Place Strike Rate Rank <= 3
Bet Type = LAY

I encourage others to share the systems they find. If you post it as above then its easy to run a future test in a week, month, year when there is more data in the database and compare the results. You can then see if the system held up over time.