Zimplit is the easiest CMS (Content Management System) ever made. Zimplit is extremely lightweight, simple and customizable. It’s easy to install, and easy to use via a simple web interface.

Features

• Its simpler than any content management system
• No admin area – you just log in and edit on-site
• You don’t need a database – all data is there, in HTML pages
• Zimplit is 100% search engine friendly
• You can set up your own website in 5 seconds
• Zimplit is Open Source and free forever

Website: http://www.zimplit.org

Demo: http://www.zimplit.org/download.html

Pligg is an open source Content Management System (CMS) available to download for free. Pligg has perfected content management in a unique way that encourages users to participate and control the content on the site.

Some of its features are:

• Article Rating
• Support for Multiple Languages
• Live Ajax Newsfeed
• SEO Enhanced
• URL Blocklist

Add additional functionality to your Pligg site without having to alter the Pligg code. There is already a large library of modules to choose from that will greatly enhance your Pligg site.

Some notable modules are:

• Multiple Captcha Systems
• Akismet Anti-Spam
• Google Adsense Revenue Sharing
• Newsletter Management
• Image Upload

Website: http://www.pligg.com

Demo: http://www.pligg.com/demo01/

Download: http://forums.pligg.com/current-version/

Alfresco is an open source enterprise level CMS application.

It provides document management, collaboration (in beta), records management, knowledge management, web content management and imaging.

Alfresco is built with Java & can be installed in both Window & Linux environments via “all-in-one installers”.

Some features of Alfresco:

• Web Content Management
  • Web content authors can access and contribute content
  • Simply preview in-context changes to any web page or web application
  • Reduce the risk of error with simple a virtualization of changes against a live site
  • Use your tool of choice, such as Dreamweaver, for web interface development
  • The ability to preview in-context changes to any web application, including PHP, Ruby, JSF, Tiles, Struts, Groovy and .NET
• Document Management
  • All content is available via a shared drive interface
  • All content is available from within MS Office
  • Work in an MS Office environment for authoring and viewing
  • Save, version, share, search and audit
  • & many more..

This application is great for any company who wants to manage all the information from one central including websites, documents & knowledge.

Requirements: Java Enabled Server

Liferay, with 60 tools and a selection of today’s most innovative technologies, enables you to do everything like:

• Creating websites.
• Building intranets.
• Simply getting the right documents and applications to the right people.

Liferay inlcudes web publishing, content management, collaboration and social networking.

With the role-based authorization, admins & users can define which information can be viewed by which users.

A strong set of community features help creating communities, user groups & they can have their own mini-portals.

Some other included features are: wikis, forums, instant messenger, calendar, webmail, blogs & more.

And, any other applications like accounting, sales can be integrated with its open architecture.

The application is “giant” with the features it offers & hard to describe its capabilities completely. Users interested in creating an enterprise portal should definitely check it.

Requirements: Supports multiple OSs, applications servers & databases.

Constructr is a fresh open source CMS application built with PHP & MySQL.

With an Ajaxed backend, this CMS application uses TinyMCE for content editing & supports clean URLs via mod_rewrite.

The admin interface has:

• Backend user & right management
• Asset center for uploads
• Integrated search engine for asset
• Automatic sync after FTP-uploads
• Automatic thumb´s for image-uploads
• Integrated shadowbox-viewer for assets
• Customizable backend language (Available: DE, EN, US, CH, AU)
• Live preview  for hidden pages and content

For the frontend:

• Cache system
• File based templates
• Multilingual frontend support
• Use a frontent that fits your special needs (pure PHP and MySQL, Smarty, Flash …)
• Individual 404 error page
• Automatic RSS 2.0-Feed for every single content

Like mentioned, this free content management system is still fresh but frequently updated & looks promising.

Concrete5 is a very powerful & open source content management application which has a different approach in how it works.

It enables users to manage websites while browsing it by simply switching to the edit mode (an overlayed screen). This makes anyone who can use a text editing application administer their websites.

The application uses PHP / MySQL & built with OOP.

With a very easy to use interface, new pages can added, updated or deleted.

A simple yet effective user permission/role feature helps creating admins, editors & other types of users.

There is a built-in versioning system which simply saves the old versions of a page & who created/updated it.

The application supports templates / plugins & there is a community getting more active everyday to get support.

To see the beauty of the application, check this demo.