Drupal Gardening is a XHTML & CSS based nice Drupal Theme. Valid XHTML and CSS.
Update: The Drupal 7 version is here! It's an HTML5/CSS3 theme.
"Let these butterflies dancing first in your Drupal peach garden, then in your heart, for the beauty of spring!"
* Site name
* Site slogan
* Search form
* Primary links
* Comment user pictures
* Sidebar, Content Top, Content Bottom, Footer
See it in action: