I have a noise that sounds like .... a metal ball rolling around, in a tin can. Only does it when tranny is in neutral and the clutch out.
Push the clutch in and noise stops, let it out and noise starts.

Any ideas and or suggestions?

mine does the same thing even after replacing my clutch. i think its b/c of the added drivetrain vibrations that cam creates. i was also thinking if the motor mounts start going out that it would allow more vibration to go thru the drivetrain at idle and rattle the TO bearing... at least thats what i think is making the noise.