Themes allow you to change the look and feel of your Drupal site. You can use themes contributed by others or create your own to share with the community. Contributed themes are not part of any official release and may not have optimized code/functionality for your purposes.
You can also create a sub-theme of an existing theme. A sub-theme inherits a parent theme's resources. Read more about Sub-theme structure and inheritance.
You can also view a full index of themes listing only their titles.
Although the overall look and feel are most definitely inspired by Twitter Bootstrap, Cascade framework is not just another Bootstrap clone. Where Twitter Bootstrap puts its focus on delivering shiny user elements that can be dropped into any project and takes control of your project's overall look-and-feel, Cascade Framework is intended to do the opposite.
Lust is a a responsive administration theme based on the first version of the Ember theme that was built for use with the Spark distribution.
Lust uses sass and compass and inherits Ember's improvements to work with Navbar module (Toolbar in Drupal 8) and includes module style overrides for Views, Ctools, Panels, Media, Workbench and Features.
This is sub-theme of the AdaptiveTheme base theme, you must first install the base theme first before enabling this sub-theme, and then enjoy it! Only uses a few pictures, this sub-theme only use 1 picture, everything else is done with CSS3.
Templator is the beautiful and great theme made by Spinnext, and good template design for Drupal. Templator is responsive Theme and using "Bootstrap" the most beautiful framework css (but with slight modifications). Use Templator on your website and enjoy it!
I am still developing this Drupal 8 contributed theme. It is not ready for primetime.
My goals with the Atomic theme are to create a base theme that provides an approachable starting point for sub themes. Atomic uses Sass and a number of Compass gems: by making a few initial global design choices, you can get up and running with some sensible defaults. Partials are broken down to let you easily provide essential base styles for elements or regions, while focusing on component styles, and keeping those styles separate from layout styles.