Elegant Themes - Simple, yet beautiful WordPress themes with easy to use implementation and support.
Theme Forest - The #1 marketplace for premium website templates, including themes for WordPress, Magento, Drupal, Joomla, and more. Create a website, fast.
Rockettheme.com - RocketTheme creates industry leading premium Joomla Templates, WordPress Themes, Magento Templates...
GeneratePress - Responsive, easy to use WordPress theme
ThemeFuse - ThemeFuse is a store that provides high-quality designed WordPress themes to let you stand apart from the crowd.
ThemeGrill - ThemeGrill is an online marketplace that develops and sells WordPress themes and plugins that you can buy to create professional websites for businesses, magazines, and blogs.