Kronolith is the Horde calendar application. It provides a stable and featureful individual calendar system with integrated collaboration and scheduling features. It makes extensive use of the Horde Framework to provide integration with other applications. It implements a solid, stand-alone calendar system, allowing repeating events, all-day events, custom fields, keywords, shared calendars, iCalendar support, generation of free/busy information, and managing multiple users through Horde Authentication.
XWiki is a WikiWiki clone written in Java that supports many popular features of other Wikis like the Wiki syntax, version control, attachments, security, and searching, but also many advanced features like templates, database and dynamic development using scripting languages (Velocity, Groovy, Ruby, Python, PHP, and more), an extension system and skinability, J2EE scalability, an XML/RPC remote API, statistics, RSS feeds, PDF exporting, WYSIWYG editing, an Office viewer and importer, and a lot more.
Chamilo is an e-learning and collaboration platform. Chamilo is currently used by more than 7,000,000 students around the world. Governments, private companies, public and private universities, and NGOs use the Chamilo software suite to manage activities from simple live training to full distant learning, certification, and staff selection.
GroupOffice is a groupware suite that takes your office online, implementing online collaboration and CRM. It allows you to share projects, calendars, files and email online with co-workers and clients. It is easy to use and fully customizable. It also features synchronization with PDAs and Outlook.
OpenXava is a framework to develop AJAX JavaEE/J2EE applications rapidly and easily. It allows you to define applications only with POJOs, JPA, and Java 5 annotations. It is feature rich and flexible. It generates JSR-168 portlet applications (Liferay, WebSphere Portal, Jetspeed, etc.).