Microsoft's SideShow system - a secondary sub-display running off of a Windows Vista system - has never been as popular as the company might have hoped, but now they're turning to gamers to rejuvenate the concept. The idea is a roughly 6.4-inch touchscreen, switchable between portrait and landscape orientation, which would present game-specific controls and free up the main display.
In that way, an RPG title could shift its control palette to the SideShow display, leaving the main monitor for the primary interface, while a racing game could offer a separate rear-view mirror. Complex games such as flight simulators could use SideShow to keep often-referred-to data such as mapping and instrument panels viewable all the time.
Microsoft aren't flailing in the dark, either. The company claims to have run a research study earlier on this year, in which gamers apparently said they'd be keen to have such a display. WiFi or Bluetooth, rather than USB, has also been suggested, so you could place the screen next to your keyboard or somewhere else more usable. No word on whether such devices will reach the market, however.