https://c1.orckestra.com/

If you develop a website on top of the open source CMS and forum support is all you need, this is for you.

https://sourceforge.net/projects/aspnet-cms/

http://www.aspcontentmanagement.com/

ASP Content Management is designed to make the creation and updating of your site a quick and easy task. Add, edit, and update all pages from your web browser.ASP Content Management Systems.

https://diem-project.org/

Diem packages many site-independent features in a clean user interface. Most of the common problems a web developer has to face up ( SEO, admin generation, search engine... ) are made easy.

https://croogo.org/

Croogo is a free, open-source, content management system for PHP, released under The MIT License. It is powered by CakePHP MVC framework.

http://www.xwiki.org/xwiki/bin/view/Main/WebHome

http://www.xinco.org/

xinco DMS™ is a powerful Web-based Information and Document Management System (DMS) for files, text, URLs and contacts, featuring ACLs, version control, full text search and a fully web-based client.

http://webman-cms.sourceforge.net/

Webman is a professional content management or website production system. It was used in more than forty big websites in Germany. (look at the history section)

http://webeditor.sourceforge.net/index.html

webEditor is born with the intention to become a helpful tool for the web content management

http://velocity.apache.org/

Velocity is a Java-based template engine. It permits anyone to use a simple yet powerful template language to reference objects defined in Java code.