My publisher, O'Reilly Media, through O'Reilly Labs offers a anatomical peek at any book they publish. For example, you can learn that Smart Home Hacks consists of 395, 370 words, 128 code examples, and 177 figures. Aside from being fascinating in a navel-gazing fashion (for me, anyway), it's useful for gauging the contents of books you might want to buy.
Another really nifty tool from O'Reilly Labs is Code Search . It allows you to search the source code examples from almost 700 O'Reilly books; over 123,000 examples in all. For example, this search returns nearly 100 sample code blocks that relate to Python and mail.