Technologies that have not been invented (yet)

Phones with Holographic screen and projector.

Bored of watching that video on your phone's small screen? Hey presto, the video projects on a wall. Want to project your PowerPoint presentation on a wall, but feel lazy to connect the projector to your computer? This phone is the solution. Your friends are crowding around you to see those photos you took on the beach during last summer? Tell them to have a seat and then project the photos on a wall.

Hoverboards

Its Not the usual ones that we see today but hoverboards that can actually lift us off the ground. They might even give us the sence of flying and when/if it is invented, it should get a lot of buyers regardless of how much dangerous it might be.

Flying car.

It would be the next private jet, just more expensive, it is more of a possibility than most other inventions that seem to be coming only hundreds of years from now because we already have flying machines in the air so why not make a smaller one and try?