-Web Stack (MySQL)
LAMP stack is a popular open source web platform commonly used to run dynamic web sites and servers. It includes Linux, Apache, MySQL, and PHP/Python/Perl and is considered by many the platform of choice for development and deployment of high performance web applications which require a solid and reliable foundation.
-Real-time document collaboration
Etherpad Lite is a real-time collaborative editor, sort of like a web-based multiplayer Notepad that allows groups of users to simultaneously edit a text document, with the ability to display each author's text in their own color. There is also a chat box in the sidebar to allow meta communication.
-Cutting Edge Content Management
Joomla! is an award-winning Content Management System (CMS) for building websites as well as a Model-view-controller (MVC) Web Application Development framework. Features include page caching to improve performance, RSS feeds, printable versions of pages, news flashes, blogs, polls, website searching, and language internationalization.
-Content Management Framework
Drupal is an open source content management platform licensed under the GPL. Equipped with a powerful blend of features, Drupal can support a variety of websites ranging from personal blogs, corporate brochures and large community-driven websites.
ASP .NET on Apache with Mod Mono
-Free .NET hosting
Mono has an open source implementation of ASP.NET 2.0, ASP.NET MVC and ASP.NET AJAX that can be used to host ASP .NET web applications on Linux. This provides a great free alternative to Microsoft's proprietary .NET stack. Apache is used to pass off requests for ASP.NET pages to the embedded Mono application server.