Came across this very useful post for those obsessed with defining how Word Of Mouth (WOM) marketing and its various incarnations work. Quoting from the Media Guerrilla and Word Of Mouth Marketing Association (WOMMA):
Buzz Marketing Using high-profile entertainment or news to get people to
talk about your brand.
Viral Marketing Creating entertaining or informative messages that are
designed to be passed along in an exponential fashion, often electronically or
Influencer Marketing Identifying key communities and opinion leaders who
are likely to talk about products and have the ability to influence the opinions
Evangelist Marketing Cultivating evangelists, advocates, or volunteers who
are encouraged to take a leadership role in actively spreading the word on your
Grassroots Marketing Organizing and motivating volunteers to engage in
personal or local outreach.
Community Marketing Forming or supporting niche communities that are likely to share interests in an industry or a brand.
Social Media Marketing Using social tools to engage audiences online.