If you've ever watched Star Trek be it the old series or some of the newer series, you've seen the characters using tricorders. The tricorder is a little medical diagnostic device that is widely used in the Star Trek universe. People have been working to make the tricorder real and there is even a tricorder X prize for the first researchers to make a functional device.
A researcher named Dr. Peter Jansen has developed a new handheld mobile computing device that is crammed full of sensors modeled after the tricorder. Jansen has been working on the project since 2007 and has designed it to be easy for other users to replicate. The doc has made complete schematics for two of the four models available under the terms of the TAPR non-commercial licensing agreement.
The different tricorders all use Linux software that's available under the GPL license. One of the tricorder model schematics available is called the Mark 2 tricorder, and it is more the sophisticated of the models available. It runs Debian Linux and uses an ARM920T-based Atmel microcontroller with a clamshell form factor. Inside the clamshell is a pair of OLED touchscreen panels. This device uses six AAA batteries for power and integrated sensors are able to measure temperature, humidity, atmospheric pressure, magnetic fields, color, ambient light level, GPS, and the distance to the surface. It can't peer into the body of a redshirt just yet.