Sky is a minimal, center aligned, CSS-based, multi-column layout theme, with Color module support (7.x only), that uses HTML5 and CSS3.
The Fusion base theme and Skinr are required. Skinr for Drupal 7 (dev release) is usable now but it is recommended that you proceed with caution and do some of your own testing.
Corolla is a highly stylized colorable theme for Drupal 7 with many theme settings to allow you to completely customize the look and feel of your site.
Pixture Reloaded is a re-colorable theme powered by Adaptivetheme and inherits all its features such as mobile support, powerful layout engine and more.
Rubik is a clean admin theme. It features a set of icons for admin pages provided by Drupal core and aggressive styling to reduce visual noise wherever possible.
BlueMasters for Drupal by More than (just) Themes is based on the homonymous PSD template, which was designed by Wendell Fernandes and released for Smashing Magazine and its readers.
Corporate Clean for Drupal by More than (just) Themes is based on the homonymous PSD template, which was designed and published by Zsolt Kacso.
Tao is a base theme for Drupal that is all about going with the flow. It is not
meant for general-purpose use, but instead takes care of several tasks so that
Danland is clean, simple, elegant, and beautiful theme for Drupal 6.x and Drupal 7.x.
Marinelli is a 3 column, tableless layout theme with a wide image banner and a "top-tabbed" primary-links system.
Here you can try a live demo
Fusion is a powerful base theme, with layout and style configuration options built in that you can control through Drupal's UI.
Adaptivetheme is a powerful theme framework designed from the ground up to power modern, cross browser/cross device websites using responsive design techniques.