The Ubi-Camera is a concept device being developed by a research group at the Institute of Advanced Media Arts and Sciences in Japan, and unlike most other concepts we've seen, this one is actually mostly functional. It takes that wonderful cultural touchstone of holding up your fingers to make a mock-viewfinder, and transforms it into a functional camera.
At this stage, the Ubi-Camera is a small device that straps onto the end of one finger. By pressing your thumb against it hard, it snaps the shot. The real trick is the infrared sensor it uses to calculate the zoom — it measures the distance between the camera and your face, and from that figures out how much of your surroundings you want in-shot.
While this concept camera is able to take photos, it's still very much unfinished. The infrared sensor isn't always accurate, it has a fixed focal length lens so all zooming is digital, and it's tethered to a computer. Nonetheless, it's a working concept, and one that will hopefully bear fruit.