Theme Forest - The #1 marketplace for premium website templates, including themes for WordPress, Magento, Drupal, Joomla, and more. Create a website, fast.
Founders Nation - Find or become a startup cofounder
ThemeFuse - ThemeFuse is a store that provides high-quality designed WordPress themes to let you stand apart from the crowd.
CoFoundersLab - Meet 250,000+ entrepreneurs online
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.
Findnlink - Find people to work with on your ideas.