Each book has dedicated Web pages, accessible only to those who have registered their purchase of the book. Microsoft even use this feature in their CD-ROM encyclopaedia, Encarta '97. Another version of this approach is to debate issues raised in a book on-line. A Web site contains discussion on the many controversial issues raised in the book. Relevant items in the news are also considered.
Readers can directly make points and argue with the author and each other in such forums.
The key to this problem is that readers cannot be charged for accessing Web pages. This forces the information provider, rather than the reader, to pay for the material. While some academic journals charge authors to print their work, this is unlikely to work in the textbook world. Unless Web sites can encourage sales of related books, they provide no revenue. This situation will soon change.