Drupal is free and open-source content management system (CMS) written in PHP which allows you to manage online content and communities. It is extremely popular for its Scalability for managing very high traffic websites. But the feature which distinguish Drupal from other content management systems is the control it provides you, with Drupal you can manage each and every aspect with custom presentation of content and designing abilities.
Drupal positioned itself for broader use unlike other content management systems. It can be used for Blogs, News websites, Portals, Social Networking Sites, E-commerce websites and more. Technically, Drupal can be used to develop almost any type of website, you only need an idea.
Currently I am designing my first theme for Drupal, for this I am stumbling upon various websites for design inspiration. Here is list of some well designed and deployed Drupal websites which I liked above all.