A common product to many marketing offers is an ebook, but not all ebooks are created equal. Once an ebook is written it can be sold or given away to promote another product or product line. Content can be written by you, or written by a ghostwriter for you, or you can purchase private label rights [PLR] on an existing ebook that you can modify, re-title and re-brand.
Ebooks are a good way to add value to a promotion. If you have written a new ebook then you can pick up some PLR ebooks to complement and increase the value of your offer.
Many of the ebooks bundled with promotions deliver content in ways that leave room for significant improvement. For example, some of the obvious features of a book are table of contents, headers or footers with page numbers, chapters with titles and sometimes sub-titles. If any of these hallmarks are missing from an ebook, then it can be improved.
If your product is too short to include the main traits of a book listed above, the terms booklet, report, or special report can be just as effective for promotion. Conversely, you can abstract content from PLR books or articles to supplement your project.