In space, no one can hear you scream. This is a problem, since if you're screaming in space, there's a good chance you desperately need surgery for one reason or another. To address this, the ESA has come up with the fancy little hat that uses augmented reality to turn just about anyone into a skilled surgeon, even in spaaace.
The European Space Agency has developed a system that they're calling CAMDASS, or Computer Assisted Medical Diagnosis and Surgery System. The system has three parts: there's the head-mounted display (HMD) for whoever's playing doctor, an ultrasonic examination tool, and a set of tracking markers that are placed on the hapless patient. The HMD is like a pair of video goggles with external cameras and those cameras can stream video of whatever you're looking at back to your eyes, with a computer in the goggles adding helpful little virtual markers and tips. The goggles can track the examination tool along with the tracking markers on the patient's body, and tell you exactly where and how to poke and prod.
The pic below shows what a CAMDASS user sees through the HMD, with augmented reality alignment cylinders and step-by-step instructions:
Since this system is just a prototype, it's only being used for ultrasonic examinations and not for anything that involves cutting people open with knives. The eventual goal is to slim the whole thing down, cram it full of diagnostic and procedural programs, and send it to the developing world, Antarctica and into space as a self-contained system that can turn anyone into enough of a medical expert to do what needs to be done.