Sign up for an account (totally legal in the US)* and fund it with a checking account electronic check.* Then make 1 $5 bet per day and get the $5 back the next day.* For example, pick a race and bet $5 to show on the favorite.* Show is for the horse to come in 3rd.* You get the $5 back the next day and if the horse comes in 1, 2 or 3 you get the winnings too (typically $5.25 for a favorite to show).*
Favorites typically show 69% of the time, giving this method an expected value of $108.68. You can't lose $ since you get the $5 back daily.