Anyone know of any case where someone used knife throwing effectively in a fight?

My view is that it is a stunt. I know there was a thing called "combat knife throwing" (or something like that), that used a specially balanced knife that remained point forward in flight.

http://paladinplanet.blogspot.com/2011/06/greatest-combat-knife-throw-on-record.html

87 ft. 87. Wow, and it isn't a joke.

The story indicates it was a lucky hit. Hit the base of the skull, with the knife thrown in a high arc.

Yeah, it could be a distraction.

Mother in law threw a knife at the father in law before the divorce. She missed, but the knife stuck in the wall behind him and IIRC ended the altercation. I think mostly he was surprised to realize she was really willing to kill him . . . and if she hit him most likely it wouldn't be point on and even if it was it wouldn't likely cause much injury. She is probably lucky she missed, if she hit he likely would have been pissed . . .

I love throwing knives for fun, but would never throw one away in a fight.

Although the skill could work in a pinch with an improvised weapon. When I took Kung Fu lessons the instructor trained to use his belt as a weapon as well as throwing coins like throwing stars.