At the most basic level, you can use PowerPoint to reveal the standings of said competition to the audience. At major conferences, this is sometimes done at great expense using an audience response system (ASR), which involves wireless keypads and a computer application that function independently of PowerPoint, run by experts.
If your budget doesn't support a full-blown ASR, you can keep score manually and put up a slide like the one shown in Figure 1.
Figure 1 An animated Excel chart can generate tremendous excitement when it shows who's in first place for a corporate T-shirt.
When the "Mochas" in the example realize that they're in first place to win the championship of...well, anything, they'll cheer and high-five each other, I promise you. In addition, the other teams will become energized by their realization that this is for real.