Like Jake, I prefer to see finishing moves that either a) appear to do some real, high impact damage... b) have a significant story behind it... or c) have an explanation as to why a wrestler who suffers the maneuver may be pinned or forced to tap out.
1. The Cross-face Chicken Wing. The move basically incapacitates an opponent. It appears to effect the neck and the shoulder, and leaves only one, non-dominant arm to fight or fend (or tap out for that matter). Wrapping up the legs makes getting to the ropes for a break a pipe dream.
2. Batista-Bomb / Power Bomb. I love the story behind the "banning" of the Power Bomb, and Batista does it better than pretty much anybody I've seen. He has so much power, and sets the move up well. Kevin Nash seemed to do it without regard for the opponent by jacknife "tossing" him, but I know he was good at it. Sid set it up well, but seeing him botch it too many times takes him out of it.
3. The Superkick. The reasons I went with "Sweet Chin Music" is because it is hands down among the most effective moves in the game. It can be measured and built up, but it can also be quick strike and sudden. The idea of a side crescent kick under the chin is the same concept of an uppercut in boxing. Take it on the chin and go down.
4. The Ankle Lock. While once ineffective due to the fact that an opponent had two arms and one leg free to move, Kurt Angle proved that it can work to one advantage to have the high ground, being able to roll with an opponent and, unlike moves like The Sharpshooter, allowing the person holding it to adjust. Also, when he first layed back and grapevined an opponents legs, the move went to a whole new level.
5. The Swanton Bomb. Maybe the only visually impressive (or as Slyfox would say, "Spot Monkey") move on my list, anybody who has ever botched a front flip off a swimming pool diving board and done a "back flop" knows how much impact you can hit with. Hardy isn't big, but the swan part of the dive adds impact the way the jacknife action in a frog splash does, and the move could legitimately knock the wind out of someone, making it hard for them to muster up the power in the ribs and air in the lungs to kick out.
Again, I like my moves to be based on "I know it's not 'real' but if it was, what would the result of the move be?