If your website have hundreds of categories with each having their own sub categories and so on so forth. Then this Responsive CSS Mega Dropdown Menu is for you.
Download Simple CSS Overlay menu.
Ladda a beautiful user interface approach of integrating progress indicators in HTML buttons. It give a nice user experience as it immediately gives feedback to user that his/her requested operation is underway.
AdminLTE is a lightweight, featured pack, open source and fully responsive Admin Panel template. It is built using Bootstrap 3 framework and features six themes and can be configured for more.
Gentelella is a free responsive admin panel template created and managed by colorlib. It is packed with powerful jQuery plugins and built using Bootstrap a solid framework for responsive development.