Prototyping is pivotal to design innovation, collaboration, and creativity. My group's research empowers more users to design interactive systems, expert designers to be more creative, and programmers to engage in more design thinking. Our research has introduced techniques for users to demonstrate interactive behavior, sample existing design elements to create new ones, and tightly integrate the creation and evaluation aspects of design. In much of this work, examples both created and harvested play ay a powerful role. We explore these issues on mobile, desktop, web, and sensor-based platforms. We seek to understand the fundamental psychological and social ingredients of design excellence in order to create more effective design tools and practices. We create prototypes that envision future interface styles; a current project looks at the future of mobile interaction.