have a new text field appear based on list selection Options

[goatberg]

I have a select list/menu. There are several values from which to select (in this pull down menu). The behavior I am looking to create is that if certain values within this list are selected then an extra text field appears so that the user can enter additional information. Is this possible?

I am thinking javascript must be used. Any help on how this can be accomplished or which javascript functions to use with a list are appreciated.