Anchor CMS, from their own words, is a super-simple and lightweight blog system. Although many blogging applications market themselves as lightweight I wanted to take a deeper look.
Koken is a free and self-hosted CMS (PHP-MySQL) that is focused on building websites where portfolio/gallery is in the core (like designer or photographer sites). It was built for publishing images, videos and slideshows as fluid, responsive media elements.
Zotonic is an open source web framework and content management system, built with Erlang. It is flexible and designed to support dynamic, interactive websites and mobile solutions. Zotonic is fast and suited for basic websites to complex distributed applications.
Forward is a developer-centric e-commerce platform which can be easily customised with coding, templates and expressive syntax. It has been developed as an alternative to the existing e-commerce CMSes that are way too complex to customise.