We used to give cash awards for:
Category winners (if not finished in the money)
Record breakers - someone breaks a league record
All-star game MVP
We thought awarding $$ to category winners would keep interest for those that were lower in the standings. But by definition this idea was rarely taken advantage of as teams that won categories usually finished in the money.
Record breakers was fun, but hard to keep track of. After our league had been around awhile they became further and further apart and the pot would build a little too high.
All-star game MVP was to increase interest and attendance to our annual All-Star game party.
We have since ditched all these when we extended money slots to 7 teams (of 20). That has done absolute wonders for the competitiveness of our league and is probably the best decision we've ever made.