Thought of a few more.
Jordan winning slam dunk contest and basically redifining the contest in 87. That image still gives me shivers.
Vince Carter again making the slam dunk contest relevant in one of the most famous non-regular season or playoff performances of all time when he won in 2000.
I seriously can't think of another more famous event that wasn't part of regular competittion. Maybe Jordan in 87 or Spud Webb in 86. I guess Pete Rose running that guy in the MLB ASG is pretty big.