Transparent screens just aren't very practical these days -- bigger models are frequently expensive and bulky, while smaller heads-up displays tend to have very narrow viewing angles. However, MIT may have solved all those problems at once with its prototype nanoparticle display. The device creates color images on a glass surface simply by 'tuning' a silver nanoparticle coating until it lets only certain light wavelengths pass through. The technique is both cheap and compact, since it requires little more than the coating and some off-the-shelf projector technology. There's also no need for beam splitters or mirrors, so you can see the picture from just about any angle. While there's a lot of work left before there's a finished product, researchers note that their display would be as easy to implement as window tinting; don't be surprised if MIT's screen shows up on a car windshield or storefront near you.