Public rewards indicate to the rest of the group those behaviors you feel are desirable. If you make a verbal commitment to someone for a reward, be sure to follow through on it. Forgetting that you made this promise demonstrates a lack of sincerity. Be sure to reward the right people for the right reasons. If you aren't sure who made key contributions to a successful project, find out before you present any rewards.
Rewards can be monetary or nonmonetary.
Talk to your people and understand what rewards they feel are significant. The corporate culture will have some influence in selecting feasible rewards. It may be easier to give someone a substantial, but noncash, award, such as a trip to a conference or trade show. Some companies reward employees with frequent flyer miles, which can be purchased from airlines for a few cents per mile. If someone does an exceptional job on a project, he or she might appreciate a mini-sabbatical, a couple of weeks set aside to work on whatever he or she likes.