An E-book that includes your marketing message and a link to your website is a proven technique in viral marketing. This method uses the multiplication effect to “explode” the distribution of your message by willing participants. This is the basic principle that was used by Hotmail to get established. When the two founders set up their free email system, all the messages that were sent by subscribers had a text message at the bottom which identified Hotmail as the origin. People who sent emails to their friends advertised the free email site.