Try this on for a concept. At the fourth Microsoft sponsored Next-Gen PC Design Competition, Avery Holleman, a student took home first place. His design is described as a “multi-user, multi-interface, modular computer designed for creative professionals to collaborate and bring their greatest ideas to life.”
The interface is very simple. Some pens and some napkins. “When powered by the pen the Napkin is multi-touch input display that responds to human touch as well as the pen.” Check out more here.