It looks like Apple could have an answer to that for its iMacs, which are all-in-one desktop systems. According to a recently-discovered patent found by AppleInsider, it seems that Apple has explored the idea of potentially adding projectors into the iMac, which in turn would allow the computer to digitally expand the display of the computer.
The patent’s description reads, “The rear housing wall may have a glass portion or other transparent structure through which projectors project images onto nearby surfaces and through which image sensors and other optical sensors receive light. The housing may be supported by a stand. An electrical component in the stand may interact with an electronic device on the stand. Wireless circuitry in an external item may wirelessly couple to wireless circuitry within the housing.”
As you can see in the diagram above, Apple envisions the projector to be capable of projecting images from the back of the computer onto a flat surface like a wall. It is a pretty clever idea, although given that this is a patent, there’s really no telling if Apple has plans to actually make it a reality.