I originally presented Tweaking Your Theme at WordCamp Louisville. I originally intended it to be more of an introduction as it was not to delve deep into code and was just a start. I hope some of the tips and information help you if you are newer to WordPress theme development.
If you have any questions, feel free to ask via the comments on this or even on Slideshare. If you are on Slideshare, I recommend that you follow me on Slideshare as well as I deliver a different presentation at each of the WordCamps I speak at.