osgGtk is a library of C based Gtk+ and C++ based Gtk-- widgets to support OpenSceneGraph (OSG) applications. The library also includes several example applications such as osgviewerGtk and osgviewerGtkmm.
OpenSim - Open Simulator. Primarily a 3D simulator for multiple indoor and outdoor mobile robots. Includes 3D real-time rendering (via OSG) and a physics engine (via ODE). Current emphasis is on manipulators.