For me, it's mostly about the Foxy mangiggle and the mancrying (TM crystalkirk) ;-D
1. Jack weaves from blood loss as part of his marathon effort to save Boone (Really, all of "Do No Harm" is just ... angst heaven.) And Jack: You can have my blood! I'm a unversal donor!
2. "Lumberjack?" ;-D Gun handoff! "Be safe, Sawyer."
3. Jack breaks down when i.d.'ing his father's body.
4. Jack tells Shannon about Boone - with no dialogue.
5. "Better or worse?" Jack helps Sawyer find the right pair of glasses.
6. Jack giggles madly after being saved from going over a cliff by Locke
7. After taking care of everyone else right after the crash, Jack wanders off to tend to his own wounds (leading to shirtless moment #1). And that's Jack in a nutshell, really.
8. RighteousAnger!Jack kicks Ethan's ass. And then kicks it some more.
9. Jack's approving smile when Sawyer shows up at the golf course
10. Jack's amused grin after Hurley produces the battery he got from Danielle
11. Jack plays the piano on the night before his wedding
12. Jack finally - FINALLY - gets mad at Kate for lying to him in "WTCMB"
13. Jack goes ballistic at Boone's funeral when Locke shows up
14. Jack's hurt expression as Sawyer tells him "I'd let you die"
15. "Why are you so interested in my father?" Jack opens up to Sawyer, but then the moment is lost.
16. Jack's humble, almost shy expression as his bride-to-be calls him "My hero."
17. Shirtless moment #2: Jack strips off to escape a swarm of bees
18. Shirtless moment #3: Jack races into the water to save Boone from drowning
19. Jack snaps at Locke for not telling them about the hatch sooner
20. Jack gladly accepts more bottles of booze aboard the plane and reassures Rose everything will be OK.
21. When the raft sails, Jack tells Walt to look out for his father, instead of the other way around.
22. His goodbyes to Jin and Michael - simple and heartfelt
23. ... what did I miss? Can't think of a fave Jack/Kate canon scene right now! "Verbally copulating," maybe, but that's really more about Charlie.
Jack flirts with Ana Lucia at the airport - although he was (by the show's timeline) extremely angry and pissed off and griefstricken moments earlier at the airport counter. And he somehow doesn't take offense at her mentioning his recently deceased father as a pick-up line! </rant>
Every time Jack forgives Kate or fails to ask her what the hell her crime was.
Failing to just jump Sawyer already. ;-D