I think that making games is at least as much fun as playing them. And for sure gamedev takes the first position in my personal “happiness per line of code” chart. If you never tried to write your own game before – just do it and believe me you will open a whole new world.
I wrote a book about gamedev, “Pro Android Web Game Apps” that was published by Apress in late 2012. It is not really limited to Android, it is more about HTML5 gamedev with mobile focus.
My other passion is teaching. There's nothing more rewarding than somebody saying "now I understand how it really works". Taking a concept that looks hard and breaking it down to a harmonic system of simple parts is a challenge. You can only do it if you perfectly understand it yourself. The second challenge is to present those concepts right: with code, words, diagrams or whatever makes learners grasp that ideas.