Open Source 3D/Game engine
before everyone rushes off to implement their own c# 3D engine I would like to point out that there are two open source .net codebases ripe for adoption into XNA.
the Axiom engine, a c# port of the well respected OGRE engine ground to a halt a year or so ago. The XNA community have much to gain by ressurecting this basically complete renderer
http://axiomengine.sourceforge.net/wiki/index.php/Main_Page
realmforge GDK, a .NET MMO Game engine based upone AXIOM - originally open source, has now gone commercial under a new name (and new codebase aparrently), but the original source of this remains available
http://sourceforge.net/projects/realmforge
for this kind of community open source is the way to go...

