Tangible objects placed on interactive surfaces allow users to employ a physical object to manipulate digital content. However, creating the reverse effecta??having digital content manipulate a tangible object placed on the surfacea??is a more challenging task. We present a new approach to this problem, using ultrasound-based air pressure waves to move multiple tangible objects, independently, around an interactive surface. We describe the technical background, design, implementation, and test cases for such a system. We conclude by discussing practical uses of our system, Ultra-Tangibles, in the creation of new tangible user interfaces.