Google Book
Google Book is a Ruby wrapper to the Google Book Search Data API.
Usage
require 'google/book'
entries = Google::Book.search('deleuze')
entry = entries.first
puts entry.title
=> "Difference and repetition"
puts entry.isbn
=> "9780826477156"
puts entry.cover.thumbnail
=> "http://bks0.books.google.com/books?id=..."