Some specific topic in one of the following general areas:
Leibniz's logic: e.g. its relation to Aristotelian logic, relation to Boolean logic, intensional vs. extensional interpretations, plural quantification.
Leibniz on language: e.g. its relation to 'mentalese', to Chomsky's deep grammar, to international auxiliary languages, his nominalism, his take on innate ideas.
Leibniz's epistemology: his theory of confused concepts, thesis of the existence of the subconscious, and/or of 'blind thought'.
Leibniz's ontology: say, in comparison with Deleuze's: the fundamentality of difference and change; or in relation to Russell's, on the importance of relations; or in relation to Whitehead's views on process.
Leibniz's theory of contingency: does he have two accounts, as is often alleged, one in terms of incommensurability, one in terms of hypothetical necessity?
Leibniz on free will: e.g. how does his claim that determinism is presupposed by an autonomous free will fare when compared to modern views?
Leibniz on space and time: e.g. his critique of Newton and Clarke, his use of the Principle of the Identity of Indiscernibles, how his views compare to Ockham's, or to Smolin's.
Leibniz on the affects (emotional attitudes): e.g. how his views compare with modern interpretations.
Alternatively, you could expound and critique any of the interpretations of other Leibniz commentators among the readings for the course.
Or, come up with your own topic. Run it by me first in any case.