Of the Explorer Society PDFs released thus far, this is probably my favorite.  While I understand the reasons it's set to be free, I'd have gladly paid a couple of bucks for this.

Short version, it's a look at alcohol consumption in the various nations of Theah, and Andrew (the author) gives a lot of solid information on the types of libations served in each nation, covering not only what each of the major nations drink but also their traditions while drinking; for instance, it's considered polite in Vodacce to let the host drink first after a toast, and drinking before your host could be seen as a sign of great trust or a great insult.

There's also a number of fun adventure hooks tucked away in here, such as Heroes' efforts to earn themselves a prized bottle of Chateau Soliel du Montaigne, or to perhaps track down one of the increasingly rare Vodacce-made bottles of 'Montaigne du Falisci.' Or perhaps put their liver to the test by claiming to be of Inish descent in an Inish village as a means of making allies, or simply unwinding at Castille's annual La Fiesta de Borachos (which can provide a good reason why any Castillian male Hero might drink in moderation).

Given that most Heroes tend to be amidst the social elite (even if on the lower rungs), they'd probably know a thing or three about their native nation's drinks and drinking customs, and with a price tag of free this simply is too good to pass up.