I just re-read the OP and I must emphasize that Revtim wishing for the smokey death of Mr. Murder is not necessarily sadistic.
You must derive true pleasure for the act to be true sadism.
The families of victims of violent acts never actually feel pleasure that the perp suffered or was executed. They feel numb. If they feel anything it’s usually a sense of justice that the bastard won’t be able to ever terrorize another human being.
The Ryan, I’m not avoiding the question, it just doesn’t make sense. I mean, can you think of any situations in which love is a useful purpose, in itself? I think both of my examples demonstrate how a bit of vengeance can produce desirable justice.
Lissa, you wrote:
Hey, just be glad I didn’t include the vivid descriptive text of how my vengeance helped me get even with the four girl scouts that kept cruelly harassing me by pounding on my doors and screaming at the top of their lungs in their shrill little voices! 
Gaudere, OK, I’m backing off because the debate between us is really lexicological in nature. The masses might agree with your definition for “vengeance”, but the masses would also agree that Montreal is the capitol of Canada.
Not in either of the above cases.
Thugs and insurance corporations are invulnerable to intelligence: you can’t come near them with the stuff. The “system” favors the rich. When I am rich I plan on using the “system” a whole lot more!
I don’t think so. . .if I didn’t take it personally (and want to ‘teach the old coot a lesson’) I wouldn’t have been half as perseverant as I was.
Not self-defense, because I was in no danger. It was my brother I was defending/avenging.
It would be great if vengeance was eliminated, and I think it will certainly happen just as soon as all crime disappears from the face of the planet.
Anger and vengeance, used with wisdom, are deadly weapons against injustice and powerful tools for building a stronger society.
(Woops, I think some of my testosterone-induced aggression slipped in there after all!)
Yet to be reconciled with the reality of the dark for a moment, I go on wandering from dream to dream.