This document discusses various types of social media that can be used for e-marketing purposes. It begins with an overview of word-of-mouth (WOM) marketing and viral marketing, explaining how viral marketing spreads content exponentially similar to a virus. It then covers several social media types - online forums for content sharing, podcasts which allow audio/video subscriptions, and social news sites where users submit and rate links. For each channel, it provides background information and discusses how marketers can utilize them, such as creating targeted podcast content or leveraging the viral aspect of social news sites.