Lucane is a free groupware platform written in Java, designed with extensibility in mind. Some applications are bundled with the platform, like a peer to peer quick message service, client/server and peer to peer file sharing, shared drawing, multi-user chat, audioconf, forums, a shared calendar, and more. The platform as a whole provides easy development for your networked applications with an object based network protocol, client/server and peer to peer integration, user and groups management, internationalization, and more.
Red-Piranha is a search system that can actually learn what you are looking for. It can be used as a Web page, command line, or XML-WebService, so it will work with most languages, including Java, Perl, C#/.NET, and PHP. It includes learning abilities for the Desktop/Internet search functionality. All feedback from the user is stored in (editable) XML and RDF, and is used by the system to improve the quality of searches.