Game Creation with XNA/Mathematics Physics/Physics Engines
Physics Engines 
Should introduce, and discuss some physics engines, compare and evaluate them, best with examples. Also show capabilities, maybe compare with non-XNA physics engines.
- Farseer 3.0, http://farseerphysics.codeplex.com/
- JigLibX is a specially for XNA designed C# port of the Physic Engine "JigLib" http://jiglibx.codeplex.com/
Other examples can be found here: http://forums.create.msdn.com/forums/t/7574.aspx
XNA physics engine list can be found here: http://www.xnawiki.com/index.php?title=Physics_Engine