The tiny Proteus motor, at only 2.5 times the width of a human hair, is small enough to enter the bloodstream and perform duties previously requiring some surgical slice-and-dice.
Researchers at Australia's Monash University developed the tiny motor to minimalise the risk of certain, more invasive surgeries. After being injected into the bloodstream, it can carry a camera and other sensors to monitor a patient without the danger that cutting and sewing presents. To move, it uses a spinning tail that spirals at 1295 RPM, and uses piezoelectricity (which uses mechanical stress to create electrical potential) for energy.
Oh, and here's my required Fantastic Voyage reference: This bloodstream sperm motor is named for that movie I never saw! [GizMag]