Tony defeating the two hitmen sent after him, which ends up pulling him out of the depression he'd been sinking into.
Carmela and Hugh's respective rants against Livia during her funeral after party are two of the most satisfying scenes to watch in the whole series
Valery, the Russian from "Pine Barrens." He gets his windpipe crushed by Paulie and is presumed dead so they tape him up in a carpet and throw him in the trunk of their car. Some time later they open the trunk and he had chewed through the tape. They march him through the snow into the woods and despite wearing only his pajamas he shows no sign of discomfort while Christ and Paulie are both freezing. When they tell him to dig his own grave he boasts "Cocksuckers. I'll kill you both. You think the cold bothers me?! I wash my balls with ice water. This is warm. You American pieces of shit!" before kicking both of their asses with a shovel and running off. The guys chase after him but can't catch him, even though the only shoes he's wearing are slippers. Paulie manages to shoot him in the head but he immediately gets back up and keeps running. Then he disappears and is never seen again. It's revealed that he was in Russian special forces and single-handedly killed sixteen Chechen rebels. There is an implication that he climbed a tree to hide from Paulie and Chris, then went back and stole their car but he is never heard from again.
Season four's finale "Whitecaps"; the scenes where Carmela and Tony confront each other over their respective adultery (Tony literally, Carmela figuratively in terms of her confessing to having fallen in love with one of Tony's associates) stands as one of the finest moments of the show's run.
Carmela: Who knew all this time you wanted Tracy and Hepburn? Well Tony, what about all the thousand other fucking pigs you had your dick in over the years? The strippers, the cocktail waitresses, were they all your best friends all of them too? You fucking hypocrite.
Artie, the meek civilian, confronts mobster Benny Fazzio outside his home and ends up assaulting him - against all odds, Artie actually wins this fight. This triumph is short lived though, since Fazzio later shoves his hand into boiling sauce.
Sal Vitro, the innocent gardener who accepts Paulie's protection and goes through a Trauma Conga Line throughout Season 5 and 6A, has been mowing John Sacrimoni's lawn for free for a year. In the episode "Moe 'n Joe", with Johnny Sack's imprisonment and allocution, and the sale of his home to Janice and Bobby, Sal humbly asks Tony to free him from this obligation. When Tony initially refuses, Sal shows tremendous balls by pressing for it. He gets his wish, giving the man at least some small respite.
The ending of "Stage 5", when Phil decides he's not taking shit from anybody anymore, followed by Catlin's baptism with a Revealing Hug between a dissapointed Tony and a fearful Chris, effectively pointing out that nothing will be the same anymore. Very chilling and underscored by the haunting song "Evidently Chickentown". Watch