I've just joined bookins.com another site for us book lovers. Here is my available list: www.bookins.com/---/2M42c0/ , which I did dutifully label with bookcrossing numbers. I like that the books are free, just like here, but the person requesting the book pays the shipping expense and all of that is handled by bookins. They e-mail the sender a shipping label that you print and tape to the package and just drop it in your mailbox--voila, no trip to the post office.
I'm happy to mail any of my bookcrossing books via bookins. If it's not on the bookins list, just let me know and I'll add it.
I'm still providing books for the shelters, stop by and drop a few off or start a crossing zone at your own local shelters.
Have a great summer.