iPads don't just want to be touched, they want to be PLAYED!
Someone recently tipped me off about a property of UITouch called pathMajorRadius, which basically tells you how much surface of your finger is in contact with the glass. It measures in millimeters, and even works with multitouch, tracking each finger tip individually in realtime.
When I plugged it into tappr.tv, it made a HUGE difference in the expression of the wands. Without any marketing, people started discovering and exploring it very rapidly, and the content being published has been absolutely amazing. We now have hundreds of dances published using touch expression in beautiful and creative ways. For example, check out this dance: