Open Source CMS With A Drag & Drop Interface: ImpressPages
ImpressPages is an open source CMS application where you can create and edit while browsing.
Creating new themes requires only the knowledge of HTML-CSS and with the help of a drag 'n' drop interface, texts, videos, photos (or photo galleries) and even forms can be inserted quickly + positioned as you wish.
The application is SEO friendly with the URLs generated, automated sitemap and ability to edit meta tags for all pages.
Multilanguage websites are handled in a very flexible way; once a new language is added and the content is created, users can be auto-forwarded to the language matching the setting of their browsers.
There is a built-in newsletter module where you can collect e-mails and send good looking newsletters to users.
ImpressPages also has many other features including RSS support, spam protection for contact forms, logging + error-reporting for the administrator and more.