Here is some info to go with my WordCamp Milwaukee talk on Theme Choices, When To Have A Baby.
In this presentation I talked about developing with different types of themes including parent themes, child themes, theme frameworks, and starter themes. Some of the specific themes I talked about were TwentyEleven, Thematic, Hybrid, Genesis, and Underscores.
I also talked about splitting up design and functionality, and when to use a functionality plugin. View the presentation slides to learn more.