Amazon.com Inc. announced today it had acquired Goodreads, a book recommendation web site that claims 16 million members who have posted 23 million reviews to the site. The purchase price was not disclosed.

Both companies emphasized the potential for the reviews posted on Goodreads to integrate with the Amazon Kindle e-book reader.

“Amazon and Goodreads share a passion for reinventing reading,” says Russ Grandinetti, Amazon vice president for Kindle content. “Goodreads has helped change how we discover and discuss books and, with Kindle, Amazon has helped expand reading around the world. In addition, both Amazon and Goodreads have helped thousands of authors reach a wider audience and make a better living at their craft. Together we intend to build many new ways to delight readers and authors alike.”

“I’m incredibly excited about the opportunity to partner with Amazon and Kindle,” says Otis Chandler, the Goodreads CEO who founded the site with wife Elizabeth in January 2007. “We’re now going to be able to move faster in bringing the Goodreads experience to millions of readers around the world. We’re looking forward to inspiring greater literary discussion and helping more readers find great books, whether they read in print or digitally.”

The acquisition gives Amazon another tool to compete with the book publishers it’s increasingly butting heads with. Three major publishers—Hachette Book Group, Penguin and Simon & Schuster—last month launched a similar site, Bookish.com, where readers can post their recommendations.

Amazon and book publishers have clashed over Amazon’s discounts on best sellers, and Amazon Publishing directly competes with established publishers with its own book imprints, such as Montlake Romance and the Thomas & Mercer line of mysteries and thrillers.

Amazon is No. 1 in the Internet Retailer Top 500 Guide.