Website owners can now become Google eBooks affiliates by linking their sites to the Google eBookstore for any of the hundreds of thousands of titles available for sale, earning commissions for their referrals.

Google launched the program as a limited beta in December 2010, and starting this month is inviting all interested site owners to apply to join the expanded Google eBooks affiliate program. Participating sites gain new revenue streams by giving their book-reading audiences an easy way to buy Google eBooks.

Google eBooks affiliates become part of the Google Affiliate Network (GAN). After joining GAN, affiliates can subscribe to the Google eBooks product feed to get links to the full set of available eBooks. To query a more targeted set of eBooks, affiliates can use the new Google Books APIs.

Visit the help center for more information and to sign up to become a Google eBooks affiliate.