Dynamic Drop Down Population

System

Can someone fire me an example of the best way to have one drop down boxes data populate given the choice of another drop down box. I tried with little sucess to use the
Interwoven provided example of this in the userscript\locations dct.

Basically, I have two items and I want the first selection to drive the choices of the second item's drop down

Also based on a drop down selection in an item - has anyone ever used radio buttons to drive the second item.

Thus, in the first item if someone selects foo - I want the
radio button to allow input from three choices (good, bad, ugly) - otherwise the only choice from the radio buttons is good