You learn more from failure than you do success. In this post, I'd like to list my mistakes and failures from versions 0.01 to 0.99 of the DTraceToolkit, as lessons to learn from.
— The Wall: DTraceToolkit 0.XX Mistakes

Great run down from Brendan Gregg on what he did wrong with his DTraceToolkit and how he'd do it better now he knows better.