Ok, let me see if I've got this right--this is such an amazing idea that I am still incredulous: you have in your possession a book, preferably one you like. You sign in to this bookcrossing site, and they send you a label to put in your book (presumably one you print out?). You put the label in, then leave the book in some public place and hope that whoever picks it up will also contact the site?

Jo, I saw that one person had left a book in a Ladies' room. That doesn't sound particularly appetizing to me, somehow. What about a Dr.'s office? :-)