The Smashwords retailer report for Apple reports sales (even for free books) by country, so you can see where your books are going. I gave away a copy of The Sixth Discipline to someone in "Country_FI" but I don't know for sure which country that is. My first guess was Finland, but I really don't know for sure. I can tell "Country_SE" is Sweden because someone there bought a copy of No Safe Haven and since it says they paid 25 SEK, I could Google that and see it's Swedish krona.
Mostly my foreign sales are in the UK, Canada, and Australia but every now and then I see sales in places live New Zealand or Spain, and lately The Sixth Discipline has been very popular in Germany.
In a way, it's a little like traveling to those exotic places to know my books are being read there. Well, not nearly as much fun, but still kind of cool.