book crossing is one of those wonderful ideas that adds some adventure to the participants life. you can release book into the wild for others to hunt =) i just love this idea. all you have to do is to sign up (for free) and start hunting or releasing books.
here is how it works:
after signing up to bookcrossing.com you can register your book and label it with a unique tracking number the website will provide you with. now release it where ever you want (just make sure it is in a safe spot) and tell people about it (again over the website).
now to hunt it people just have to go to the section about recently released books, find it in the spot you left it and report that this book is cached!
if you own a small business you can even open a safe zone for free books that people will leave.
i would really like to hunt some books here in israel but it does not seem to be very popular or well known of here... only some tourists leave books in hotels somewhere in jerusalem. if someone wants to start some hunting with me just let me know and we will get it started =)