I wrote this when I was the Digital Library Applications Lead at the University of Notre Dame. It was archived from http://www3.nd.edu/~dbrubak1/ which no longer exists.

Service Excellence

Hierarchy of User Needs From Designing for Emotion by Aaron Walter
A line drawing of a pyramid. Starting from the base the layers are labeled as functional, reliable, usable, and pleasurable. The peak of the pyramid is indicated to be missing.