Genesis

Genesis is an standards compliant, accessible and semantically rich starter theme for Drupal 6. Genesis is easy to theme yet extremely flexible, giving you endless theming possibilities. Genesis makes building a standards compliant accessible theme easier than starting from scratch.

A few sites seen using Genesis:
http://design.acquia.com
http://www.myappleguide.com
http://laptopblog.gr
http://adaptivethemes.com
http://www.drupalcampireland.org
http://www.calthorpe.com
Key Features

* Standards compliant—XHTML Strict, CSS3
* Modular CSS
* Flexible layout options
* Built in support for theming site sections
* Gpanels - multi-column, fluid grid micro-panels
* Content source ordered for SEO
* Choice of 3 starter subthemes (including a dark starter theme)
* No complex logic in templates
* Advanced dynamic CSS classes
* Conditional Styles module included