Three years ago, I built a website for a Superbowl watch party at my house. We invited about a dozen friends to answer 20 questions like "How long will the national anthem be?" and then kept score as we watched the Superbowl.
Everyone had a lot of fun, so I've kept it up the last few years - always refining the concept with better questions, graphics, scoring, etc.
This year, I decided to make an iPad app out of it and put it on the app store titled Superbowl Party iPad App.
Please check it out if you have an iPad. It's a good way to keep everyone engaged during your Superbowl party.