In writing about the "Multiseat" Computer, which allows up to 12 people to share one PC, I forgot about the similar unit from nComputing , which was on display at ACEC08. The nComputing unit has PCI cards which is inserted into a PC running Microsoft Windows or Linux and allows it to be shared by three or five people. . The nComputing unit uses Ethernet type cable with RJ-45 plugs to locate the users up to 10m from the PC.
Another option might be to use USB external video cards. These are intended to provide a second screen, usually for a Lpatop, where a PCI card cannot be installed. They would have the advantage that a single standard USB cable could be used to connect the video, mouse, keyboard and audio for the user, making a low cost computer terminal. The catch would be that the USB connection could carry a fast moving high resolution video image. But this might be good for a web terminal, which just displays relatively static web pages. Amazon sell two models of USB external video card from IOGEAR: GUC2020DW6 USB 2.0 External DVI Video Card and the GUC2015V External VGA Video Card.