Becoming co-winner of WWE Tough Enough 3. He's also the only winner of the contest still in WWE, and the most successful superstar the show spawned; unless you include the contest which was run on SmackDown, when he's only second to The Miz.
Note that Josh Mathews was also a Tough Enough contestent and actually has a longer tenure than either one of them. However, unlike John Morrison or The Miz, Josh ended up as a regular commentator in no small part due to his small size.
His TLC match with Sheamus. It's widely considered his greatest match, as well as the one that broke him through into the main event scene.
Hell, ALL of the matches during that feud with Sheamus. Every single one of them is considered to have been a show stealer. This includes beating a Daniel Bryan match. Let that sink in for a minute.
Tops that by catching himself during Royal Rumble '11, then using his Parkour skills to move about the barrier and then JUMP from it and to the steps before heading back into the ring.
To clarify: Morrison was thrown over the top rope and onto the apron, and was then sent flying into the barricade, but caught the top of it with his arms and its side with his feet. His tightrope and jumping act ensured his feet never touched the floor, and so kept him in the Rumble. He even got a nice kick to William Regal's head in after reaching the steps.
To further clarify, when he actually got eliminated, it took 4 guys to take him out. Usually, that kind of force is needed for the uber-giants like The Big Show.
And gave a repeat performance of awesome at RAW the next night, during a RAW Battle Royal for the No 1 contender for the WWE Championship at Elimination Chamber. About half the match was focused on Morrison avoiding being eliminated in the most insane ways possible.
On top of that, when John Cena tried to hit Morrison with the Attitude Adjustment, Morrison countered the move in mid-air and landed on his feet.
Just about everything in 2011's RAW Elimination Chamber match, but especially the cross-body splash he gave to Sheamus from the top of the dome.
Don't forget his TRIPLE JUMP FLASH KICK on Punk in the closing moments of the match.
Extreme Rules 2011. Starship Pain onto twoguys from near the top of the cage? (keep in mind that when he normally does the move he springboards off the ropes near the turnbuckle) Holy shit...
John Morrison and the Miz vs. HBK and Rey Mysterio. HBK hits the Sweet Chin Music on the Miz, apparently sealing the match, but Morrison's standing right behind HBK. Cue markout.