Curiosity Has a Laser (Pew, pew, pew!)
For sheer coolness, it's tough to beat ChemCam. This instrument will fire a laser at Martian rocks from up to 30 feet (9 meters) away and analyze the composition of the vaporized bits.
ChemCam will thus enable Curiosity to study rocks that are out of reach of its flexible robotic arm. It will also help the mission team determine from afar whether or not they want to send the rover over to investigate a particular landform.
ChemCam is composed of several different parts. The laser sits on Curiosity's mast, along with a camera and a small telescope. Three spectrographs sit in the rover's body, connected to the mast components by fiber optics. The spectrographs will analyze the light emitted by excited electrons in the vaporized rock samples.
Read more about the other instruments onboard Curiosity at Space.com