I.e. A user will pick their country of residence from a drop-down, and in the second drop-down for state, they'd then only see the applicable states for that country.
Combo-Box 1 - Country:
Combo-Box 2 - State:
US - Alabama
US - California
UK - Scotland
UK - Wales
Selecting US in combo-box 1 would only display Alabama and California in combo-box 2.
I've been looking at the custom-fields part of the admin panel, and have not seen it can be done in there. Would this require an add-on?