Old books make for good door-stops. But, how many door-stops does one really need? So, for those books that could be more useful, simply cut around the front and back cover with a razor-blade and peel off the cloth cover. You may have to scrape off the excess cardboard from the book cover cloth. Cut to approximate size, and glue in place. Trim with a razor blade. I use both rubberized wood flooring glue, or double-sided tape as used in sewing. Bingo, a cloth hinge has been born.
PS . . . I fergot to note that I always paint the hinge, once it has dried, with black acrylic paint. It helps to seal the cloth, preventing threads from coming loose.