The thread creator would need to add a poll post-submission, which I don't think is possible. Plus it'd only be a one-time poll. We just need people to comment here, maybe we can sort out a new thread in the meantime or after we actually choose a book. A mod's assistance would probably be useful for that (I'm looking at you, Absurdity).
Zerkalo, you nominated another book without giving your formal vote: do you wish to cast a vote, or do you abstain? We can certainly add your suggestion to the list in place of the Hume nomination. Also, I've added in Machiavelli's The Prince for possibilities. My vote still remains on Leviathan, though.
OFFICIAL POLL COUNT:
Leviathan - 2
Everything else - 0
See post #89 for the running collection of nominations!