Dwight finally gaining the upper hand on Jim. After spending nearly all day pranking each other (by hitting each other with snowballs) he creates an elaborate prank at the end of the day, by filling the parking lot with snowmen, and it's implied that Dwight is inside one of them, waiting to attack Jim with more snowballs. He's actually up on the roof, watching Jim destroy each and every snowman.
Dwight pepper spraying Roy in "The Negotiation" when the latter makes an attempt to attack Jim. Even better after one hears his talking head interview.
Dwight: Every day for 8 years, I have brought pepper spray into this office to protect myself and my fellow employees. And every day, for 8 years, people have laughed at me. Well, Who's Laughing Now?
After Andy gets Dwight fired, Jim hides his phone in the ceiling and calls it during the day. This proves to be the trigger for Andy's total self-destruction in front of Michael and his wall-punch. Kick the Son of a Bitch indeed.
In "Traveling Salesmen", Dwight and Jim, the two archenemies, have to go on a sales trip together... and absolutely nail it with some impressive teamwork. Jim does the talking, while Dwight asks if he can use the phone and calls to another paper company. After Jim is done, the prospective client tells them he rather stays with the big guys. Dwight asks him how important customer service is to him and points out that the other paper company he called, one of the big guys, is still having him wait. Jim grabs his phone, calles to Dunder Mifflin and immediately gets Kelly on the phone. Dwight proceeds to tell the client how dedicated he is, but the latter has already heard enough: they have a deal.