WordPress Theme Resources

From the WordPress Codex Documentation on WordPress Themes

WordPress Theme Checklists

Customizing a WordPress Theme

The WordPress Loop

WordPress Theme Template Files

Resources and References for Developing WordPress Themes

Designing a WordPress Theme from Scratch

Developing WordPress Themes for the Public

WordPress Comments and Interactivity

WordPress Code Hacks, Snippets, and Customization Tips

WordPress Custom Post Types

WordPress Troubleshooting

WordPress and Typography

WordPress Collection of Theme Tips