This is a list of the work that I've done in the past.
Based on Drupal 5. Theme is completely CSS based. One of my first big Drupal projects. Used LDAP for authentication, and a considerable amount of theme customization. Flash slideshow used for the splash page. SEO optimized, etc.
I would have done some things differently now than I did back then, but I guess these things come with experience.
My first theme I had to design using their corporate identity. I didn't have very much creative freedom (or time), so I used tables for the theme. The site was developed using Drupal 5. You can still see some remnants of the bluemarine theme I based it on. Not my best work, but time was a factor.
Used Drupal 5 to create. The theme was created to completely replicate their existing site. I replaced the theme with a completely CSS based theme, while following their original table based theme as closely as possible. They liked their own design, and wanted the functionality of a Drupal based CMS.