In today’s economic climate, marketers are trying to do more with less by making more efficient media buys. The most cost efficient, and often most trusted form of media is word of mouth. Senior Forrester Research Analyst Jeremiah Owyang called word of mouth the holy grail of marketing.

Organizations like hospitals rely heavily on word of mouth to remain top of mind for patients choosing a health care institution for their treatment. Lee Aase from the Mayo Clinic presented at the Community 2.0 Conference in San Francisco on how the Mayo Clinic is using social media to share their message with the existing community and extend the reputation built over many decades through word of mouth.

As millions of new users continue to join and use Twitter, retweets are quickly becoming the most effective way to socially endorse a brand or comment. A retweet is repeating someone else’s quote or tweet on Twitter. Owyang’s blog post called retweets the core essence of viral content spreading, as the content of a retweet was so valuable and important to that user that he or she was willing to share it with their network. And Forrester research indicates that Twitter users are brand sensitive.

Retweets are one way to make measuring and monitoring word of mouth more tangible and accurate. Repeets.com, a new site launched this week by our own Adam Coomes, tracks the hottest and most retweeted tweets of the day, week and month, providing a snapshot view of the most shared tweets. Mesiab Labs has launched www.retweet.com, an online petition users can sign to endorse retweets with the hope of creating enough support that Twitter will make an official Retweet button.

The chart below shows the steady rise of retweet or RT references online. Check out the spike from April to May 2009. How is your brand using and measuring retweets?