If you are a premium member of Freesponder, our books are branded with your affiliate links. Normally, you'd use them as Lead Magnets to encourage people to join your list. But you can also freely distribute any book without asking for an email.
Without the barrier of 'signing up to a list' it's much easier to give away lots of books.
We encourage your readers to share the books too, helping them to go viral... and carrying your affiliate links with them!