Moving things (very, very, very tiny things) using nothing but photons. Not immediately useful given the scale, but this is a first and could have applications in nanoelectromechanics and biology. Originally this same principle was thought to be what powered the nifty Crookes radiometer (that black-and-white vaned vacuum bulb thing that’s now usually sold as a novelty desk toy), but that device is actually moved by thermal transpiration or temperature differences.
(If the above link is behind a paywall for you, you might try the basic Nature writeup instead)