One of the most useful, although often-unnoticed, features of Google Book Search is the ability to scan your own books and build a personal library which you can then search if Google has scanned those books.
The official Google Books blog has posted tips that now you can scan your books into the service's “My Books” feature by using a normal barcode scanner.
Google empowers the users to make their own collection of books which they can search separately from the main book search engine. The My Books segment of Google Books is similar to the popular Mac application Delicious Library in enabling you to build a list of all your titles in a digital card catalog that can be shared with others.
For instance, if you are attempting to find a passage or a information you once read but can not remember the book no matter how hard you squeeze your brain, the ability to search your personal library can come in handy.
Of course you can do this without the USB barcode scanner simply by searching for the book, this prevents the need to type in the ISBN number of books manually, in the video below, Google's Matt Cutts describes the process of scanning your books into Google Book Search like fun:
One of the benefits of building up your Google Books library is that you can limit in-text searches to just the titles you own.
Once the books data is stored in your virtual library, you can rate them and even search through them online using the Google Book Search engine. Right now, Google is merely matches your books with the books it has already digitized for search purposes only.
And what is more, if you feel concerned about giving all that personal information to Google you can also use some other Web services to do this, including Shelfari, GoodReads, and Library Thing. However Google's big ISBN entry screen is the most barcode-friendly of the bunch.