Lets take a 2nd hand car dealer as an example. A car node has a "Fuel Type" field, and the dealer has the option of selecting "Diesel" or "Petrol" from a drop down. Now, what happens when he gets in an electric Car? The user does not have the skills to edit the node type directly. And I do not want to have to go in every time and add a new Fuel Type option. I'd create a admin settings page for your site in a custom module, allow the user to define values in a text area, one per line as per the CCK field and then create function to return these. Use this function in the allowed values field on the CCK setup. Kind of duplication but lets the user change the values without being overwhelmed by all of the extra CCK widget/field settings. Hope this makes sense.