Drupal has been growing more popular with each passing day. It has gathered many users and developers from all over the world. The following are some great themes for Drupal developers.
Acquia Prosper: It is an advanced Drupal theme with a monochromatic look and neat lines. It is designed primarily as an e-commerce theme that is easy to customize, but is extremely flexible for any type of site.
Summertime: You can download it from drupal.org. It is a modern theme with fine tuned CSS. It serves great for blogs, communities and online media. This theme was designed and developed exclusively for Drupal by the RussianWebStudio.com team.
Orange: It is a CSS based theme that has only one sidebar. However, it has a few other regions for different types of content.
Conch: It uses the old wine label color as the background and dark brown content blocks above. This theme reminds you of a vintage time with its simple decorations, simple text to point the user's attention to the pictures.
Blog Grail: It is based on Holy Grail and controlled by Grid and developed as a subtheme of Zen. Other Holy Grail themes are Dark Grail and Plain Grail.