Until very recently, the typical home computer user accessed the machine's software and processing capabilities solely through the physical interfaces of a mouse, keyboard, and monitor. Everyone, from software designers to industrial designers to Web site designers, relied on these elements to be the physical-interaction method that users employed to access their product. Today, interface designers can no longer assume that the interaction between a user and a digital interface occurs only, or most effectively, through traditional devices such as keyboards, mice, and number pads. Tangible interfaces and ubiquitous-computing technologies are changing the human relationship to computing technology, and designers must take this into account when creating products and services. In this article the authors describe some of the tools available for this purpose, including proprietary, open-source, and custom solutions.