PC Magazine reports: "When Dr. Julio Bonis awoke one Sunday morning with a sore shoulder, he could not figure out what he had done. It felt like a sports injury, but he had been a bit of a couch potato lately.
... Then he remembered his new Wii."
First they diagnosed 'Space Invaders wrist' in 1981. Then in 1990 they called 'Nintendinitis', which is exactly like 'Space Invaders wrist' with a different name. Both of these aliments describe a sharp cramp that is caused by playing video games for too long.
Now in 2007 we have 'Wiiitis', which is just another name for sore muscles caused by actually doing something with your body rather then sitting... :-)