||Graphical user interfaces (GUIs) are mainly designed for a single computer and a set of single input devices. However, when we simultaneously use many and different types of computers and electronic devices, such interfaces would often fail to work. As we can combine several tools to perform a task in the real world, we consider that it should be possible to dynamically combine multiple digital devices. It should also be possible to use "direct manipulation" interfaces that work across the boundary of these devices. We call this concept "multiple-computer user interfaces". This video demonstrates several interaction techniques based on this concept, including Pick-and-Drop, a digital whiteboard system with palmtop computers, and a digital table that can recognize objects placed on it.