Word of mouth marketing has been a major part of every REALTOR's® business plan, we just tend to call it referrals. I belong to a "word of mouth marketing" group called BzzAgent. Originally I had joined with the hopes of getting free stuff, but I have found that I also enjoy being exposed to new products and being able to give my input on those products.
The latest campaign is for a book about "word of mouth marketing" written by David Balter who is also the founder and CEO of BzzAgent. It is an interesting analysis of what makes word of mouth marketing so effective, if done right, and what characteristics a good word of mouth campaign has. You can download a copy from one of many blogs or buy a copy from amazon.com.
Although it won't supply you with a step by step plan to create a successful word of mouth campaign there are a lot of good lessons to be learned about how we use word of mouth marketing, whether we know it or not. Just about every day we all give our opinions and critiques, on products and services, out to just about anyone who is interested and/or willing to listen. The question is, what are you doing to be the one people are talking about?
Word of mouth is the best form of advertising I think. As it is coming from someone who has had the experience for themselves. People will weigh that in over many other forms of advertising I think. Also word of mouth advertising keeps you striving for the best as you never want to slip up and give anyone something bad to talk about.