Gus's neighbor instantly recognizing Malvo for what he is and demanding that he leave the neighborhood. Malvo threatens to kill him and his children in response, but then he leaves the neighborhood, just as he was told. It's one of the only times in the series that anyone manages to get the upper hand on Malvo, and it's a perfectly harmless, unassuming, ordinary man who has enough guts to face up to a monster.
Lester, that meek little nobody, expertly setting his brother up to take the fall for his wife and the sheriff's murders. His shit-eating grin afterwards is something to see.
Mrs. Hess sends her two idiot boys to rough up Lester after the life-insurance policy on her husband is denied. He whips them with a stapler.
A Fox, a Rabbit, and a Cabbage
After having her work dismissed and ridiculed by Bill, it's immensely satisfying for both Molly and the audience when the FBI agents commend her for her investigation and dress down Bill for ignoring all the glaring evidence that's been sitting in front of his nose for almost a year.
A very understated one, but when Malvo visits Lou's diner, Lou recognizes what, if not who, he is, and casually kicks the supports out from under Malvo's 'philosophy' by pointing out that animals only kill because they have to to survive, but sociopaths like Malvo kill for fun.
After spending the whole show being obtuse and unhelpful regarding Molly's investigation, Bill finally steps up in when he orders Lester to answer the FBI agents questions regarding Linda's death, basically saying "You're not bullshitting your way out of this one pal" with just three words.
Bill: Answer the question.
Lester successfully fending off Malvo, forcing him to retreat bloody and injured. This is followed by Gus finding his hideout and popping him full of holes.
Then there's the end, where Lester meets the end he so richly deserves courtesy of a weak patch of ice.
The final scene. Molly simply snuggles up to Gus as they watch television as a typical, happy family. And then cue the familiar cinematic theme.