In my experience, incentive schemes come to two ends:
1. They level off - plateau. When a scheme reaches a certain point, usually 3-7 years from inception, there is no more "productivity, efficiency, or savings" gains which can be realized.
2. The goals are constantly being set higher and eventually are unattainable. At this point, employees become frustrated and usually leave the organization.
Non-monetary rewards:
Public recognition - in the organization's monthly bulletin; Periodic (quarterly/semi-annually) off-site award/recognition event - invite spouse and children.
Personal recognition - Plaque/certificate from organization head; A day off to spend with family; Fulfill an employee's "wish": a practical, non-work related, legal response, within reasonable cost guidelines, to what an employee wants.
Just some thoughts,
PALADIN