The Goodreads app is geared at helping readers discover new books that interest them and offers reviews, recommendations, and more. One of the coolest features is the barcode scanner, letting users scan in books that they have found (likely in a bookstore or library) and add them to their "to-read" shelf. Better yet, Goodreads has a feature that'll help you better decide whether you'll like a book or not before you buy it.
