osgSceneMaker Sourceforge

Open Scene Graph Website   

Delta3d assets library Delta3d is an engine that uses OSG they have created many impressive 3D models(.ive and .osg)

Delta3d Website   The Delt3d website has some useful tools for any OSG users.  I especially recommend the particle editor

osgEdit  A utility for editing osg files also

 L3DT Large Terrain Editor.  Very cool terrain creation tool.