There was a great article on Emotional Interface Design on Carsonified.com by Aaron Walter The interfaces we design must first be functional – they need to solve a problem for us. Next, they need to be reliable – no fail whales please. Our interfaces need to be usable – easy to learn, easy to use, and easy to remember. The piece we often overlook is the pleasure. It’s at the core of culinary arts, but we find it far too infrequently in the web apps and websites we use daily. But what I liked best was this image: http://carsonified.com/blog/design/emotional-interface-design-the-gateway-to-passionate-users/