Interested in exploring the universe? Open-source tool developer Peter Jensen has created a device much like a Star Trek tricorder, using mostly off-the-shelf parts that were soldered in his toaster oven.
The small device, which Jensen calls the Arducorder Mini, uses a PIC32MX795F512L with 128k of RAM and 512k of flash. It includes an array of sensors, including a radiation sensor, a magnetometer, x-ray and gamma ray detector, a light sensor, a gyroscope, accelerometer, temperature sensor, and a spectrometer.
Source files for the device are available online, as are detailed build instructions.