Kinect's potential for gaming might not have been thaaaat great, but its applications for other things, like cheating at pool and medicine, have been pretty impressive. The team at Microsoft Research Cambridge, for instance, have rigged one up to peek inside skulls and look at brains with kindasorta x-ray vision.
Using the Kinect's stereoscopic cameras, special software can keep track of how your head (or a dummy's head) and figure out exactly how a brain is sitting in there. Obviously it's not real x-ray vision because it's just projecting a brain, not the brain, but even the approximation could prove handy for neurosurgeons when they're getting ready to do some probing.
The admittedly hacked-together prototype system uses a tablet with a Kinect literally taped to the back of it, but it certainly wouldn't be hard to work out a better model. This would be a dream app for Google Glass, but you'd be hard-pressed to pull off the same effect with just a normal camera. But head-mounted or not, seeing inside of people—even if it's just what they're supposed to look like—without cutting them open is a neat trick for pretty much anyone to pull off.