Yesterday I downloaded D&D Manager. I played around with it and immediately began to find places where it could be improved. Instead of pestering the designer about my issues I decided to try and improve it myself. Being the programmer I am I went back to the site and downloaded the source code because it was licensed under GPL. I opened up the project and began trying to figure out what was happening. I quickly learned that it relied heavily on Core Data and that I knew next to nothing about Core Data.
Several hours later I was working on my own implementation and busy enjoying the wonders of core data. I'm still working on my project and learning new and interesting ways of using core data. My implementation is no where near complete but I have already figure out all sorts of cool things I can do with it