What the customer wanted
There is an old cartoon which depicts several different versions of a tyre swing. The various panels show the evolution of the concept - as marketing requested it, as sales ordered it, as engineering designed it, etc... The final panel in the sequence shows "what the customer wanted".
What's the point of this story? Too often in business it seems to me that people simply don't listen to what the customer wants. Granted, many of the concepts we deal with are pretty abstract, and it is impossible to climb inside someone's head and truly see what they are seeing, however more often than not, a typical supplier response is effectively - if you don't like our solution, then you must have the wrong problem.
Keep it simple! Don't be afraid to read back to the customer what you think they want - far better to get the details correct up front than to go down a winding road which ultimately won't satisfy anyone.
Don't forget - everyone has a customer. Try and listen to them!