E-books may be the wave of the future, but some important books and authors are not riding that wave. Some writers or their estates object to e-books on principle (J.K. Rowling, Tennessee Williams); some think the royalty rate is too low; some doubt the market for older titles is sufficiently large; sometimes the contractual issues are just too complicated. But such big-name holdouts as Tom Clancy, Danielle Steel, and the estate of J.R.R. Tolkien are starting to come around.