Combo Boxes that Allow New Values to be Added

An age old question. How can we use a combo box to add new values to its list, “on-the-fly”?

This question has been answered thousands of times, and people keep asking it. Well, I am adding my voice to the side of the answers crowd in the hopes that at least 1 person will not have to ask.

To read my version of the answer, visit Not-in-List.

p.s. This one comes with a sample database!