Those move's that you screamed "OOOOH" the first time you saw them. The one's that done the wrong way could really screw someone up.
Psycho Driver - Easily could destroy someones spine and i'm honestly surprised it hasn't.
Brainbustaaahhh - One foot too far and your skull crashes into the post. need I say more?
Styles Clash - I've seen a few videos of this one. The person doesn't bend all the way back and their neck is broke.
Tombstone Piledriver - Undertaker is smart and keeps their head way above the danger zone but done wrong it could easily fuck your neck up
Lionsault - This isn't really dangerous to the opponent more to the person doing it. EX: Hayabusa
Codebreaker/66 Tears - Either version is really dangerous. Jericho's version is the least dangerous cause he gets you in the chest, the other version i've seen is worse. I forget who it was in a japanese video I saw who made his opponent bite through is tongue and also broke his nose with it. I gave myself a concussion when my opponent dropped me on my head while I was doing it to him. (go watch BZW Rage 2010 it's at the end)
Any Inverted Brainbuster - Some people can take a clear drop to the top of the head but most people I know can't handle that pressure on their neck. One wrong move and paralysis is sure to occur.
That's really All I can think of but I'm sure I missed a lot of them. Which moves do you guys think are the most dangerous?