Mercutio: "Ask for me tomorrow, and you shall find me a grave man." His dying line is a pun! I should hope to die so well.
Friar Laurence's Get a Hold of Yourself, Man! speech to a hysterically suicidal Romeo in Act III Scene II; he reminds Romeo that he was lucky to be banished instead of punished by death, lucky to have killed Tybalt when Tybalt tried to kill him, and killing himself will essentially kill Juliet.
The 1936 film features the only sword fight that Basil Rathbone got to win in his acting career, despite being a far more skilled fencer than many of his opponents.
The massive opening battle in the 1968 film, with practically every single servant fighting. One guy is even seen fighting three opponents at once! And Lord Capulet gets on the action too, wielding his gigantic longsword and managing to cut down one Montague who tries to attack him.
Tybalt's entrance in the Baz Luhrmann film. Badass personified.
The guns. A real work of art for any gun enthusiast. Besides, crazy as it may seem, there's nothing cooler than seeing the cast of Romeo and Juliet kicking ass with 9mm's.
Tybalt's "I AM FOR YOU" just before the fight with Mercutio was probably the most badass point in the whole play.
Mercutio's most (in)famous line: "A plague o' both your houses!" after his swordfight with Tybalt he shouldn't have died from.