Adding Values 'on the fly' to Field-based list?

[Wickerman]

Hi - Me again, with a second question for the same scenario I just described. . .

Q2 -- What is the best way to allow users to add new Actor names "on the fly" as they work? Is there a way of doing it in this same portal, or must I build an interface for an "Add new Actor to List" process --perhaps in a separate window?

I'm thinking also of situations where I want to use a 'Join Table' to track subject keywords relating to each film, where I want the user to build the lexicon as she goes, adding terms to the Keyword table as needed as she assigns them to specific films.

thanks again for any pointers.

Albert