Abstract: If dark matter exists, the only way it is guaranteed to couple to visible matter is through gravity. Trying to directly detect dark matter in a terrestrial laboratory through this coupling would be very difficult due to the weakness of gravity. However, it has recently been suggested that an array of quantum-limited mechanical sensors could be constructed to detect heavy (roughly Planck-scale) dark matter candidates purely via gravity. I'll review the basic idea, some applications to other (non-gravitational) dark matter detection, and some current experimental work.