Qt is a comprehensive, object-oriented development framework that enables development of high-performance, cross-platform rich-client and server-side applications. When you implement a program with Qt, you can run it on the X Window System (Unix/X11), Apple Mac OS X, and Microsoft Windows NT/9x/2000/XP by simply compiling the source code for the platform you want. Qt is the basis for the KDE desktop environment, and is also used in numerous commercial applications such as Google Earth, Skype for Linux, and Adobe Photoshop Elements.
Redland is a set of C libraries providing a high-level API for the Resource Description Framework (RDF), allowing it to be stored, parsed, serialized, queried, and manipulated. It has an object-based, modular design and comes with detailed reference documentation and examples. Redland supports all RDF vocabularies such as FOAF, RSS 1.0, Dublin Core, DOAP, and OWL, the query languages SPARQL and RDQL, and all RDF syntaxes including Turtle, RDF/XML, RDF/JSON, RSS, Atom, RDFa, and GRDDL.
ROOT is an OO framework for large-scale scientific data analysis and data mining. It contains an efficient hierarchical OO database, a C++ interpreter, advanced statistical analysis, visualization, introspection, documentation, networking, and GUI classes. The command/scripting language is C++, and large scripts can be compiled and dynamically linked in. Using the PROOF (Parallel ROOT Facility) extension, large databases can be analyzed in parallel. The system runs on all known POSIX platforms, Windows, and MacOS X.
Scope is a framework built around an extensible implementation of the Model-View-Controller (MVC) pattern. It provides an easy-to-use Java library that can be used as a basis for component-oriented application development following the layered architecture detailed in Sun's J2EE and in Cheesman/Daniels: UML Components. Scope ships with three View implementations: one for Swing GUIs, one for servlet deployments using XML/XSLT, and another for JSP applications. It has been used commercially as a foundation for development of a VoiceXML UI.