I heard an NPR piece just the other day about a serendipitous book sharing idea:
The "3 Rs" of BookCrossing...
Read a good book (you already know how to do that).
Register it here (along with your journal comments), get a unique BCID (BookCrossing ID number), and label the book.
Release it for someone else to read (give it to a friend, leave it on a park bench, donate it to charity, "forget" it in an airliner seatback pocket, etc.), and get notified by email each time someone comes here and records journal entries for that book. And if you make Release Notes on the book, others can Go Hunting for it and try to find it!
I've signed up! You should too!