I agree with some of the remarks shared about the disconnect between some organization's actions and their mission statements. However, I think that's the fault of management and how they work to develop or carry out the organization's mission. Surely some mission statements may end up to be just a page of sweet words, designed to attract uninformed shareholders or employees alike. For a mission statement to work, it must become a part of the fabric of the organization; and, it must represent the ideal and be referenced voluntarily at all levels. It's the leaders job to bring this about. The mission statement provides a sense of purpose and meaning; when an organization's behavior does not match it's company mission statement it's worse than if no mission statement existed at all.
In 20 years of independent consulting I've served many organizations where the mission statement did not appear to match organizational behavior. Fortunately, however, I've also served an equal number of organizations that ARE their mission statement. To me, these organizations redeem the concept and value of the corporate mission statement. The key is leadership. The leaders in these organizations play in active role in defining and communicating the organization's mission through their behavior and decision-making.
On a personal level, I've found that a personal or family mission statement a powerful tool for personal decision making. Many years ago, Kathy and I developed our family mission statement. We set out to describe the successful outcome of our role as parents. That simple effort, and the sense of mission that resulted, has completely transformed our family. Though we don't have it posted on the wall anywhere (we probably should), we do refer to our mission statement often enough to remember what it says and to evaluate how we are doing, both as a family, and as parents. The result is that decisions that we make are made in the context of our family mission and we see these decisions as capable of enhancing or detracting from the picture of our ideal family outcome. I've found it much easier to make decisions about what to be, do, or have when my sense of mission is clear.
The other value I've found in a personal mission statement is that is forces us to think about what we will leave behind. Again, the mission statement, used correctly, can be a powerful tool.
Back to the topic at hand - corporate mission statements. I believe that they can be powerful or a waste of paper. Their success, I believe, depends entirely on how they are created (who's involved) and how they affect behavior within the organization (Behavior changing or lip service?)
Several years ago, I gave David a copy of a book that I enjoyed: "The Mission Statement Book" by Jeffrey Abrahams. This books takes a look at 300+ corporate mission statements from America's top companies. It also offers guidance in how to create and implement a corporate mission statement.
It's an interesting and inspiring read.