For example, I crafted a campaign for a book on building-related illness that offered a sample chapter on how buildings make you sick. The text is compelling, and almost any reader would want to know how to prevent the trauma described. The length of the giveaway is not critical. About ten pages of text is typical. Non-fiction resource lists are often much shorter.
Content is a bigger issue than length.
You should try to pick something geared toward the Internet audience. Look for passages that deal with computers or business. Cyber-fiction and science fiction work well. Anything that helps people in their careers is good. Preparation Care must be taken to prepare the giveaway for electronic delivery.