See the Following Linkshttp://silverlight.net/forums/t/1134.aspx
http://www.telerik.com/demos/aspnet/silverlight/Cube/Examples/RoomDesigner/DefaultCS.aspx
http://blogs.msdn.com/mharsh/archive/2007/04/23/3d-performance-demo-in-silverlight.aspx
http://www.dolittle.com/blogs/einar/archive/2007/05/19/3d-in-silverlight-1-1-alpha.aspx
www.dolittle.com/silverlight/3D/TestPage.html
3D Rotating by Mouse Options
http://sildev.net/3DDemo/
http://sildev.net/3DCubes/index.html
Many more examples for 3d
http://www.markdawson.org/Kit3D/