I've posted a comment on what could be an interesting discussion, specifically since the advent of Xbox 360 Achievements.
Tom DeMarco: Peopleware: Productive Projects and Teams
A must read for those who can influence software developent at any level.
Jill Butler: Universal Principles of Design: 100 Ways to Enhance Usability, Influence Perception, Increase Appeal, Make Better Design Decisions, and Teach Through Design
Invaluable design principles in no nonsense terms.