We are huge fans of Brand Wheels. Rather than a lengthy brand book it’s a very easy way of communicating the key features of the brand on one page. The wheel is divided in two with rational factors at the top and emotional factors at the bottom. The two or three most important factors are in the middle.
Of course using a brand wheel for a B2B software company is quite controversial but we would say that even B2B software buying is not an entirely rational activity, there’s still emotion involved.