If you don’t want to carry around a book you have finished here is a great way to pass along to someone else. BookCrossing is like a worldwide booksharing cafe. Once you are done reading a book register it at the website, write down the URL and the allocated ID number inside the cover, and then give them away or leave them where someone will find them.
The idea being that the book is continually passed along, and you get to track where the book goes, for the life of the book. Hopefully you will end up with a collection of well travelled books.