Holograms

This is a great site, but overwhelming because there is just so much information to get through! His diagrams are really clear, though, and it would be really cool to make your own holograms as he describes.

Probably the best of these videos on how holograms are made.

Good explanation of holograms, and why "3-D" movies don't actually give you the same type of experience—but maybe they could someday!

Maybe like this: here is a demonstration of some new technology that can project text and images in mid-air. It works by ionizing the molecules in the air to make them light up.

Another video of the same technology.

This isn't actually using holograms, but digital projection that makes things look they are present in 3-D through optical illusion and angled screens. I think these images are often called holographic.