The PenTable system combines a digital tabletop with standard PC interfaces like keyboard, mouse and LCD display for a multi-purpose workplace. In the setup, the digital tabletop is utilized as a peripheral display and direct pen input device. The thesis describes design and applications of PenTable and provides a detailed description of a special user-drawn graphical user interface (GUI) on the tabletop, which consists of sWidgets and pMenus. These elements have been custom designed for the specific requirements of direct input tabletop displays. The thesis also presents the results of a user-study which compares pMenus with standard pop-up menus on cluttered tabletops.