The 2Time Mgt Blog compares Tae Kwon Do Belt Colors to productivity mastery on eleven levels. Much knowledge can be gained from reading the individual posts. I was intrigued by the idea of seeing how to gradually improve skills on these different levels, and was motivated to create a pdf that compiles them. See the post on Putting it All Together for a sample personal development plan.
Productivity Levels (pdf)
see also: “Ready to Test for Your Belt?” from MarkTaw.com.