What the Customer Really Needed
This great cartoon showing how a product is understood and described by different stakeholders is definitely going in my toolbox for explaining project disfunction. My explanation will be that you can't start to achieve a common understanding of something until get visual. If everyone got together and drew a picture of the solution and then regularly checked in as it was incrementally built, the potential for miscommunication would be nearly zero. Proofs of concept, prototypes, and pilots are useful for communicating more complex functionality — Much better than a lengthy detailed written specification.