A generator/sensor may include a pair of arcuate swing arms having respective opposing ends pivotally carried by a base so that the arcuate swing arms are transverse to one another and define a movable crossing point therebetween. A body may be carried by the arcuate swing arms at the crossing point therebetween. At least one electrical generator may be driven by relative movement between the body and the base, such as to generate electrical power or to sense movement, for example. The body may be a pendulum mass or sail responsive to fluid flow.