Researchers from the University of Tokyo have developed 3D holograms that can be touched with bare hands. It is called the Airborne Ultrasound Tactile Display and uses acoustic radiation pressure to create a pressure sensation on a user's hands.
A retroreflective marker is attached on the tip of user's middle finger, IR LEDs illuminate the marker, and two Wiimotes sense the 3D position of the finger. This lets the users handle the floating virtual image with their hands.
In the video link below, researchers demonstrate how a user can dribble a virtual bouncing ball, feel virtual raindrops bouncing off their hand, and feel a small virtual creature crawling on their palm. First practical uses will likely be games, but real applications should follow. This is at the top of my whizzbang technology list. Now we really can reach out and touch someone, almost.