I have written a plugin for org agenda, which allows "gamification" of task management. Define currencies, earn them by completing tasks, and spend them on rewards. Inspired by HabitRPG, Epic Win and similar systems.
http://bitbucket.org/eeeickythump/org-gamify Note - I am well aware of existing criticisms of gamification. I have significant reservations about many of its applications myself. However I am not going to enter into any debate about its desirability or ethicality. I have written some software to allow individuals to voluntarily experiment with gamifying aspects of their own task management systems, in order to find out whether it is enjoyable or useful for them.