This is a short and simple starter on Gamification (about 90 pages of content).
Described as "A great primer", this is mostly aimed at people who have not yet dipped their toes into this most fascinating of subjects. Among other things, it will arm you with a basics understanding of motivation, what to use to hook into that as well as examples of its use in the real world.
Written in plain English, Gamification: A Simple Introduction, is based on many months of continuing research, conversations with experts in game design, gamification, psychology and more as well as my own experience and insights into the application and understanding of gamification.