It goes without saying that Google are not merely good but great, but that doesn't mean that they own "search" as O'Reilly have just gone on to prove.
The O'Reilly Code Search provides a means to search through their extensive catalogue. The results show the code in the context of the page on the book, and there is a link to the respective book's home page where you can buy the book or just download the examples first.
It supports attribute-based searching, so you can look for specific authors, ISBN numbers and titles, as well as the natural option to use code keywords or API names.
Of course this helps the sale of O'Reilly books, but it's also a real value-added service to their customers, current and future. My hat is off to O'Reilly both for the concept, the openness and it's execution.