We have not make too many front end modifications but did a lot of back end work.
We migrated from Invisions IPB to Drupal. Wasn't an easy task. At first, we thought maybe it would be easier to use both systems, then figured why manage both when drupal can provide a simple, easy to use interface.
We decided to stick with the default drupal theme based on a color scheme related to our logo. We tried looking for a high quality template, but even professional temples are limited.
We recently launched www.JustJobs.com also using Drupal - it's a blog covering jobs issues right now but later will become a true career site once the programming is ready.... the theme and logo are already wearing on me, so we'll probably redo them when the jobs module is done.
Teaching Expertise is a site for teachers and other education professionals. It's a place to come to get advice, share knowledge and ideas, look for jobs, buy resources for your school and, most of all, learn.
As a small(ish) UK based design company we use Drupal for nearly all our sites (I say nearly all as e-commerce is still done using alternative open source services). We have found Drupal to be so beautifully flexible and want to show a couple of our latest releases to the community to see what the other Drupalers think. We work very hard to ensure high accessability standards are met, despite fierce resistant from ill informed opposition.