There is no greater art of demonstration than that of self-defense. Not only is it a positive way to engage your audience, but it is also an effective way to empower them by demonstrating a set of skills that could one day save their life. An important topic such as self-defense is one that, with the right motivation and tone, could change a person's life. You could either invite a professional to come in to demonstrate these skills, or you could select a member of your audience to help you demonstrate them.
Since much of a person's time throughout the week is spent at the office or parked in front of a computer for long periods at a time, a good topic for demonstration would be that of simple, yet beneficial, exercises for people to do while sitting at their desk. Such exercises might include strengthening, stretching and breathing. Another exercise might include meditating and even focusing your eyes away from your work or the computer to save yourself from serious eyestrain and/or headaches. Not only is this an interesting topic, but one that could benefit your audience's health and well-being, as well.
Not everyone knows how to tie a necktie. It's one of those lost arts that many people would secretly like to know how to do, but don't. This would be a simple demonstration and would require very little research on your part. However, it might be fun to incorporate some interesting history on the necktie, as well as some of the benefits to knowing how to tie one.
Ballroom dancing is very popular these days, so demonstrating how to dance the tango would be a great way to connect with your audience. Of course, it doesn't matter whether it's the Tango, the two-Step or the Waltz. What matters is that you find a fresh way to introduce the dance of your choice to your audience. If you are an expert in the field, you might select a member of your audience to help demonstrate the steps, or you could always invite a professional in to help you.