At least until the day comes when they rise up against us, we're continuing to find useful new ways for them to serve us. The result of a challenge by Carl V. Nelson, a staff physicist at Johns Hopkins, to a group of engineering students, this simple robot made mostly of plastics was developed to find and mark the locations of land mines in rough terrain. The students rose to the challenge, building the whole thing for $5,000 (of their $8,000 budget) largely by using lots of off the shelf parts. The robot also has a camera that feeds real-time images to the remote control and beeps when it thinks it's found a mine, so the operator can decide whether to mark the location. Of course the metal-detector part is in the rear, so the robot has to roll over the mine before it can be picked up, which seems a bit odd. On the other hand, if the robot blows up the operators can be pretty sure they've found a land mine.