Swing pendulum

I need to make an animation of a sign attached to a string swing righ to left, left to right, until eventually it stops.

I have seen somewhat of the same type of thing in some of the new IBM advertisments on the net with the guy in the shirt and tie holding a waterbucket or falling through gears.

Is there a way to link parts of 2 objects together like a skeleton so when something animated it brings the other part of the other object?

Any suggestions…might be easier/involve in actionscript.

I found this little sample flash

http://www.actionscript.org/showMovie.php?id=599

Exactly what im looking for…but i need it with only 2 joints