Knowledge is a multi-platform library designed to be easy and feature complete in aid to game development.

Features:

Supports Nintendo Wii and Pc (GNU/Linux, Microsoft Windows).
Object Oriented clean API.
Common math routines such as vectors and matrices (accelerated by hardware).
Customizable render pipeline.
iD Software Doom 3 MD5 Models with skeletal animations.
iD Software Quake 3 MD3 Models with vertex animations.
Multi pass texturing.
Cameras.
Easy debugging.
XML Parsing by tinyXML.
Rendering to Texture.
Material, Texture and Resource managers.
FreeImage on Pc and PNG/JPEG/TPL on Wii.
3D Sprites.
Particle Systems.
Skyboxes and Skyplanes.
Frustrum culling.
High precision timers.
Easy file parsing and loading.

Thanks to http://www.tehskeen.com/forums/showthread.php?threadid=13597 for the news.

http://www.castorgroup.net/