If you don't want to automate the process, or just want to finish with a flourish, the best way to cap the events is to have a final medal ceremony with photographs taken during the events (see Figure 6).
Figure 6 To really get the juices flowing, the final medal ceremony can include digital photos or images taken from video shot during the exercises.
While the PowerPoint slide is animated sequentially to maximize suspense, the winners can be given their prizes when the final standings are announced.
A colleague of mine, Gregg Ketter, who specializes in such motivation and training events, even purchased some "real" gold medals to distribute at the conclusion of the events. You can imagine how motivating those medals were when shown to the participants just prior to the first corporate event. (Gregg can be reached at The Ketter Group, 626-523-2421.)
The bottom line is that PowerPoint isn't just for speaker support anymore. You can use it creatively and effectively to charge up an audience by providing scores and feedback for a wide variety of corporate events.