If most businesses had only word-of-mouth advertising, they would grow very slowly (although much more profitably). The following statistics are a big reminder to make your marketing communications repeatable--in common, not-embarrassing-to-say-outloud words. One excellent way to help your supporters is to use narrative techniques, creating stories they can re-tell in their own words.
Promo magazine: Word of Mouth the Biggest Influence in B-to-B: Survey. 2007-May-15
The executives said that word of mouth has more than twice as much influence on their purchase decisions as advertising, direct mail or press coverage. That includes (in order): recommendations from colleagues or friends, conversation with a salesperson, participation at marketing events, conferences and tradeshows, and last, the Internet. Fully 75% of these influential conversations happen in person; only 3% are conducted via e-mail, with text messaging and blogs/online chat each accounting for just 1%, the survey found.