You forgot the Hoglog. It was basically like the Eye of the Hurricane but with a legdrop instead. Also, he used the Cobra Clutch and a Swinging Cobra Clutch Slam when he was in ECW.
Damn, how could I forget those? Alright, now the list looks even more sad.
The Showstopper - standard Chokeslam
Missle Dropkick - used during 'Show's "slim days" in late 1999, most notably in his match against Viscera
The Final Cut - Eye of the Hurricane
The Alley Oop - Flapjack from a Powerbomb position
Dragonsleeper - used for a couple weeks, before Undertaker decided to start using it on his own and name it "Takin' Care of Business"
Spear (aka WWE generic big man finisher #42-B) - Used a couple times while teaming with Kane
Hog Log - The previously mentioned Final Cut, but using one of his legs rather than his arm to drop the opponent
Cobra Clutch Backbreaker - Sometimes this would simply be used as a submission. Other times though (and this definitely looked more devastating than the Showstopper, IMO), he would lift the opponent just prior to the submission, drop their back across his knee, then throw them off to the side, sometimes resulting in the opponent doing a full spin before hitting the ground.
Knockout Punch - because WWE can't decide from one week to the next whether Undertaker or 'Show is "the best pure striker in WWE"
Camel Clutch - since 'Show is now apparently a submission specialist because he's challenged John Cena to a "match he can't possibly win" at Extreme Rules
Do tag-team finishers count? If so, you got the double-chokeslam he used with Kane. I don’t remember if he and Undertaker or if he and Billy Gunn had double-team finishers though.