What are good examples of person vs. person (jealousy) conflict in Macbeth?
There are many instances of jealousy between characters in Macbeth. Macbeth is clearly jealous of King Duncan's power, but he also seems to harbor a similar, if not less explicit envy toward Banquo. Banquo is Macbeth's foil, in that he is honorable; also, in Act IV, the witches conjure eight kings who resemble Banquo ('For the blood-bolter'd Banquo smiles upon me / and points at them for this'). The message is clear: Banquo's heirs will be powerful kings. In this way, the slain man once again succeeds where Macbeth has failed (that is, in terms of having sons and heirs).
It could also be argued that Lady Macbeth is generally envious of men, who are able to wield power in ways she cannot (see Act II, 'Come, you spirits / unsex me here'). Last, toward the end of the play, Macbeth seems to envy those who are not plagued by a guilty consciousness (see Act I, especially 'Macbeth shall sleep no more').