Amazon is exploring a new Kindle subscription library service for books, according to the Wall Street Journal -- think of it as Netflix for literature. There aren't many details in the WSJ report, except that the service would be focused on older titles and included with a $79/year Amazon Prime subscription, much like Amazon's existing Instant Video service. Publishers are said to be somewhat hesitant about the idea, as they fear it could lower the value of books; Amazon is reported to be trying to allay those fears by offering a "substantial fee" for participation and potentially even limiting the number of titles customers can read each month.