Google announced an affiliate program to allow publishers promote its eBook service on their websites for a certain pay.

Google will accept publishers of a variety of websites into the program, including online retailers, blogs and book publishers.

"Starting today, we invite 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," wrote Pratip Banerji, product manager at the Google Books team, in a blog post.

There are about 3 million free titles and hundreds of thousands for sale in the eBookstore. Publishers who wish to participate can connect their sites to the program's main product feed, which gives them access to all books for sale. Besides, they can also customize multiple books available to their site by working with Google Books APIs.

Google has made eBooks accessible from desktop and mobile browsers and through applications, as well as compatible with a variety of e-book reader devices.

The eBooks service and store can be accessed from applications for the Chrome browser and for Apple iOS and Android devices. About 2.5 million eBooks applications have been installed so far.