S.E.
Another Option - go on www.bookcrossing.com and register them with a number, leave them in odd places (bathrooms, shopping carts, benches at malls, etc...and see where they end up). Totally free website where you make the world your library. I LOVE the website.
You can see anytime anyone registers finding them on the website, see what they think of the book, and see when they release it and where if they journal it...they end up all over the world. I have books all over South America, Central America, Europe and the USA. You can also trade, swap and follow them on their journeys. It is a blast!!!
It is fun to leave them places...and even more fun when you get local alerts telling you that someone dropped one of...you can "hunt" for it.
All free and you will never be spammed or anything.