This is very simple and practically anyone can do it! If you have a hobby that you love to blog about write an ebook on the subject and place the address to your blog in the book! Readers will see it and be able to visit your blog later on. This is one reason why you'll find affiliate marketers writing ebooks and giving them away for free. Another method I've found quite handy is to sell an ebook giving the buyer reseller rights but not any rights on changing any of the content. This allows the buyer to make money themselves while the original author still gets traffic to their blog!