Install a SkyCeiling from The Sky Factory and it'll feel like you've blown the roof off your house. You can choose from a Luminous SkyCeiling with its own backlighting system, or an Ambient SkyCeiling that uses existing light in the room. The company offers a tremendous variety of images for wall or ceiling applications, or you can design your own in almost any shape or size.
These are still graphics in these ceiling tiles, but as soon as flat-panel displays get cheap enough, we're going to make ceiling tiles out of LCD displays, and then feed live video into them using an HD camera pointed at the sky. Sheesh, our idea probably won't be that much more expensive than a SkyCeiling.
Product Page [The Sky Factory] (Thanks, Stephen!)